How to troubleshoot common PC problems in Windows 11: a method and fixes

A troubleshooting method anyone can follow

Technicians work through problems in a fixed order, and the version most of them learn comes from CompTIA. The A+ Core 1 exam objectives (220-1201, V15) list six steps. Since V15 the method is printed there as a competency standard rather than a tested objective, and CompTIA recommends it to anyone new to IT support. Translated for a home or office PC:

1. Identify the problem. Write down the exact symptom and any error code; a phone photo of the screen is fine. Ask what changed just before: a Windows update, a new app or driver, a new device, a power cut. Try to make it happen again, and take several problems one at a time. CompTIA's explainer lists the same moves: identify symptoms, determine recent changes, duplicate the problem, narrow its scope.
2. Establish a theory of probable cause, and question the obvious. Plugged in, switched on, charged, on the right input? Then search the exact error code on the vendor's support site.
3. Test the theory without changing anything you cannot undo: move the device to another port or PC, start in Safe Mode, see whether your phone gets online on the same Wi-Fi. If the theory was wrong, go back to step 1.
4. Plan the fix, then apply it. Back up whatever the fix could put at risk and know how you would reverse it (CompTIA's guide calls this a rollback plan). Make one change, then test.
5. Verify full system functionality. Test the whole task that failed, restart once to confirm the fix holds, and prevent a repeat if you can.
6. Document findings, actions and outcomes: symptom, cause, what you changed. It is the first thing a technician asks for, and it tells you what to undo if the fix breaks something else.

Change one thing at a time. If you update a driver, uninstall an app and reset the network in one go, you will not know which change fixed the problem, or which to undo when something new breaks. And know when to stop: a step you do not understand, on a PC that holds the only copy of files you need, is the point to hand over.

The PC does not turn on

Three failures look alike from across the room. If nothing happens at all (no lights, no fan, no sound), the problem is power. If lights and fans come on but the screen stays dark or the PC beeps, it is stuck in its firmware (the BIOS or UEFI) and usually has a hardware fault. If a logo appears and then start-up fails, the hardware has done its part and Windows is the problem, covered in the next section. Microsoft's guide to startup issues draws the same line: the first phase is the firmware's power-on self-test (POST), which ends when the firmware finds a valid system disk.

For a PC that shows no sign of life:

• Check the chain from the wall. Test the outlet with a lamp, switch on the power strip, and on a desktop check the switch on the back of the power supply and that the cable is seated at both ends.
• On a laptop, charge it, then force a restart. For Surface laptops, Microsoft's advice is to use the charger made for the device for at least 15 minutes, then hold the power button for about 20 seconds. It is a sensible first try on any laptop.
• Disconnect everything external: USB drives, SD cards, docks, external monitors. An accessory can stop a PC from starting, and Microsoft's checklists begin here.
• Look for signs of life. Microsoft's startup guide suggests checking whether the drive activity light works and whether Num Lock toggles its light; if neither does, start-up is stuck before Windows and there might be a hardware issue. Beeps and blinking light patterns are the firmware reporting a fault, and their meaning differs by manufacturer, so look the pattern up on your PC maker's support site.
• Rule out the monitor. On a desktop, a monitor that is off or on the wrong input looks exactly like a dead PC.

If you smell burning, unplug the PC and stop. CompTIA's objectives list a burning smell, capacitor swelling and random shutdowns among the symptoms of failing motherboards and power supplies, and none of them is a home repair.

Windows will not start, or restarts in a loop

When Windows itself fails, it has its own repair kit: the Windows Recovery Environment (WinRE), a small recovery system installed alongside it. Microsoft describes the trigger: the Windows loader sets a flag when start-up begins, and Windows clears it before the sign-in screen. If the flag is still set at the next start, the PC opens WinRE and runs Automatic Repair instead. A power cut during start-up can trigger it too, so one Automatic Repair screen does not prove anything is broken.

If WinRE does not appear, Microsoft's instructions are to interrupt start-up on purpose: as soon as the logo appears, hold the power button until the PC shuts down. Do that twice, and the third start should show Automatic Repair. While Windows still runs, you can get there from Settings > System > Recovery > Advanced startup > Restart now, or by holding Shift while you select Restart. If a damaged boot manager keeps WinRE from loading at all, make Windows installation media on another PC (Microsoft's recovery guide asks for a USB drive of at least 8 GB), start from it and select Repair my PC.

On Windows 11 version 24H2 build 26100.4700 or later, quick machine recovery adds a step: after repeated failed starts, WinRE goes online and checks Windows Update for a fix Microsoft has published for a widespread boot failure. It is on by default on Home editions and on Pro PCs that no organization manages, and needs a cable or password-protected (WPA or WPA2) Wi-Fi.

If that does not help, or the PC does not have it, start with the least disruptive tool under Troubleshoot > Advanced options:

If the trouble began right after an update, uninstall that update first. If it began after you installed a driver or a program, start in Safe Mode and remove it, or use a restore point. Safe Mode loads a limited set of files and drivers, and if a problem does not happen there, the default settings and basic drivers are not its cause. In Startup Settings, press 4 or F4 for Safe Mode, or 5 or F5 for Safe Mode with Networking.

A black screen with only a blinking cursor is different: the firmware cannot find a boot device. Remove any USB drive and check the boot order in UEFI Firmware Settings. If the system drive is missing from the firmware's list, it may have failed; CompTIA lists "bootable device not found" among the symptoms of a failing drive.

On a drive encrypted with BitLocker, most WinRE tools ask for the 48-digit recovery key. If you use a Microsoft account it may be saved there: open aka.ms/myrecoverykey on another device. Microsoft Support cannot retrieve or recreate a lost key, so find yours while the PC still works.

Blue screen and stop code errors

A stop code error is Windows halting on purpose, because carrying on could corrupt data. You see "Your device ran into a problem and needs to restart" with a stop code such as PAGE_FAULT_IN_NONPAGED_AREA or MEMORY_MANAGEMENT, and sometimes the name of the driver file that was running. On Windows 11 version 24H2 and later the screen is black rather than blue, but it is the same error. Photograph it. One crash that does not come back usually needs no action.

Drivers are the usual suspect. In Microsoft's analysis of crash root causes, 70% came from third-party driver code, 10% from hardware and 5% from Microsoft code; the other 15% could not be analyzed because memory was too corrupted. If the same stop code keeps returning:

1. Undo the last change. Remove hardware added before the crashes began. If a driver was updated, open it in Device Manager, then Properties > Driver > Roll Back Driver.

2. Start in Safe Mode if Windows crashes before you can work.

3. Check Device Manager for devices marked with an exclamation point, and update, disable or uninstall them.

4. Free up space: Microsoft suggests keeping 10% to 15% of the drive free. Then install the latest Windows updates, and firmware updates from your PC maker.

5. Test the memory. Press Windows + R, run mdsched and select Restart now and check for problems. Windows Memory Diagnostic runs its Standard tests during the restart (press F1 for Extended ones) and shows the result after you sign in.

6. Repair system files and the disk from a Command Prompt run as administrator, DISM first, then SFC:

   DISM.exe /Online /Cleanup-image /Restorehealth
   sfc /scannow
   chkdsk C: /f /r
   

The System File Checker reports whether it found and repaired corrupted files. On the system drive, chkdsk /f /r runs at the next restart; let it.

Some stop codes point straight at a component. From Microsoft's list of common ones:

Windows also writes a memory dump (small ones go to C:\Windows\Minidump) that a technician can open in WinDbg to find the faulting driver. Driver Verifier, which stress-tests suspect drivers, is a technician's tool too: Microsoft warns it can slow the PC and cause more crashes while it runs.

No Wi-Fi or no internet

Find out which link is broken before changing settings. Microsoft's Wi-Fi guide suggests connecting another laptop or phone to the same network: if it gets online, the problem is on your PC; if nothing does, look at the router, the modem or your provider.

"No Internet" under a connected network is precise: Windows sends a small web request to a server online, and no answer came back. The PC reached your local network but not the internet. Work through these in order, testing after each:

1. Run the Network and Internet troubleshooter: open the Get Help app and search for "connect to network and internet". Get Help's troubleshooters also cover audio, Bluetooth, cameras, printers and Windows Update.

2. Check the basics: Wi-Fi on, Airplane mode off, and any physical wireless switch on the laptop on.

3. Forget the network and reconnect from Settings > Network & internet > Wi-Fi > Manage known networks.

4. Restart the modem and router. Unplug both, wait at least 30 seconds, plug in the modem first and wait for its lights to settle, then the router.

5. Try the other band. Many routers broadcast separate 2.4 GHz and 5 GHz networks.

6. Reset the TCP/IP stack and DNS cache from a Command Prompt run as administrator:

   netsh winsock reset
   netsh int ip reset
   ipconfig /release
   ipconfig /renew
   ipconfig /flushdns
   

7. Reinstall the network adapter driver. Download the driver from your PC maker first (on another PC if needed), then uninstall the adapter under Network adapters in Device Manager and restart.

8. Use network reset last: Settings > Network & internet > Advanced network settings > Network reset. It removes and reinstalls every network adapter with default settings, so VPN software may need setting up again, and known networks may return with a public profile.

Two readings from ipconfig narrow things down. An address starting with 169.254 means Windows got no address from the router, so check that the router's DHCP service is on. And ping followed by the Default gateway address tests the link to the router: if it replies, the problem lies beyond it, at the modem or the provider.

No sound

Start with where the sound is going, then work down to the driver, in Microsoft's order:

1. Check the output device. Select the speaker icon on the taskbar, then the arrow beside the volume slider, and choose the speakers or headphones you expect. An external monitor without speakers, set as the default output, plays nothing.
2. Check the hardware and volume: cables in the right jack (on many PCs green is output, pink the microphone), speakers on, nothing muted, the app's own volume up. Plugged-in headphones can silence the speakers.
3. Run the audio troubleshooter in Get Help, or from Settings > System > Troubleshoot > Other troubleshooters.
4. Turn off audio enhancements: Settings > System > Sound, select the device, and set Audio enhancements to Off.
5. Update, reinstall or roll back the audio driver under Sound, video and game controllers in Device Manager. Uninstalling it and restarting makes Windows reinstall it; if audio stopped after an update, roll it back. Windows also has a generic High Definition Audio Device driver.
6. Restart the audio services: in Services, restart Windows Audio and Windows Audio Endpoint Builder.

Display problems and a second monitor

A black or frozen screen is not always a dead one. Microsoft's blank screen guide starts with the keyboard:

• Windows logo key + Ctrl + Shift + B resets the graphics driver; a beep or a flicker means it worked.
• Windows logo key + P cycles the display modes (PC screen only, Duplicate, Extend), which rescues a picture sent to a screen that is not there.
• A black screen with a mouse pointer usually means Windows Explorer has stopped: press Ctrl + Shift + Esc and restart Windows Explorer in Task Manager.

Then check the cable at both ends, try another cable or monitor, and look under Display adapters in Device Manager. If it lists Microsoft Basic Display Adapter, Windows is using its generic driver, which limits resolution and multi-monitor support; install the graphics maker's driver. If the screen broke after a driver update, roll the driver back from Safe Mode, and use the low-resolution video option in Startup Settings when a bad setting leaves no usable picture.

A second screen that shows "No signal", duplicates the first or never appears has its own causes: ports, cables, adapters and the graphics chip's display limit. Our guide to setting up dual monitors covers them in a table of symptoms and fixes.

Keyboard, mouse or USB devices stop working

Test the device before you test Windows. Microsoft's checklist:

• Unplug the device, wait a moment for Windows to unload its driver, and plug it back in.
• Try a different USB port. If a USB hub sits in between, make sure it has power, or plug the device straight into the PC.
• Check the cable for damage, the batteries or charge, and the keys and sensor for dirt.
• On a wireless device, press its reset button, or unplug the USB receiver for about 10 seconds. For Bluetooth, run the Bluetooth troubleshooter in Get Help.
• Try it on another PC. If it fails there too, the device is faulty.

If it works elsewhere, the problem is on your PC. Look in Device Manager for an exclamation mark on the device or under Universal Serial Bus controllers, check Windows Update for drivers, and roll back a driver that changed recently. When every USB port stops at once, restart before anything else. The A+ Core 2 objectives list USB controller resource warnings among common Windows problems, so the fault can be in Windows rather than the device.

Apps crash or will not open

When one app fails, fix the app. When several fail, or Windows features fail with them, look at Windows.

1. Update the app and Windows, then restart.
2. Repair or reset it. In Settings > Apps > Installed apps, select the three dots beside the app, then Advanced options > Repair; if that is missing or does not help, select Reset. Desktop programs have Repair or Change in Control Panel's Programs and Features.
3. Reinstall it. For an older program, run the Program Compatibility troubleshooter in Get Help.
4. Rule out other software with a clean boot. A clean boot starts Windows with only Microsoft services and no startup apps: in System Configuration (msconfig) select Hide all Microsoft services and Disable all, then disable the startup apps in Task Manager. If the app works now, something else was interfering. Turn the items back on half at a time, as Microsoft suggests, so each restart halves the suspects.
5. Repair Windows files with DISM and sfc /scannow, as in the blue screen section, when the crashes are not limited to one program.

Windows Update keeps failing

Run the Windows Update troubleshooter (Settings > System > Troubleshoot > Other troubleshooters), then work through Microsoft's general steps:

• Power and network: plug the PC in and use a stable connection.
• Administrator rights: some updates need an administrator account.
• External hardware: disconnect drives, docks and anything else not needed.
• Free space: an upgrade needs at least 16 GB free on a 32-bit system or 20 GB on a 64-bit one.
• Date and time: turn on Set time automatically and Set time zone automatically.
• Update cache: in services.msc stop Windows Update, delete the contents of C:\Windows\SoftwareDistribution, then start the service again.

The error code tells you where to look. 0x800f0922 means too little disk space or trouble with components such as the .NET Framework; 0xC1900101 points to an incompatible driver, and Microsoft's fix starts with the network and graphics drivers; 0x8007000d means corrupted files in the update cache.

When damaged system files are the cause, Windows 11 can reinstall itself in place: Settings > System > Recovery > Fix problems using Windows Update > Reinstall now. It reinstalls your current version and keeps your apps, files and settings. It needs Windows 11 version 22H2 with the February 2024 optional update or later, and may be unavailable on PCs a work or school manages. If updates fail for no reason you can find, scan for malware: CompTIA's Core 2 objectives list OS update failures among the symptoms of a PC security problem, and our guide to antivirus on Windows 11 covers what Microsoft Defender already does. For keeping updates flowing in the first place, see how to keep your computer updated.

Reset this PC: the last software fix

When the problem is Windows and nothing smaller has worked, Reset this PC reinstalls it. Start it from Settings > System > Recovery > Reset PC, or in WinRE from Troubleshoot > Reset this PC, and make two choices:

Keep my files is the choice people misread. It keeps your files, not your programs: every app you installed has to be reinstalled and signed into again, so list them, with their licence keys, before you start.

During a reset the screen can stay black for a long time, occasionally more than 15 minutes, and the PC may restart by itself; restarting it yourself can make the reset fail. Microsoft puts a typical recovery at 30 minutes to 2 hours. Remove everything with Clean data is meant for selling or giving away a PC, and Microsoft notes it does not meet government or industry data erasure standards. After a reset, the steps in how to set up Windows 11 on a new computer apply as if the PC were new.

When to stop and call a professional

Software cannot repair hardware. The A+ Core 1 objectives list the symptoms technicians treat as hardware faults; these are the ones you can notice at home:

• The drive: grinding or clicking noises, a S.M.A.R.T. failure warning, "bootable device not found", very slow reads and writes, missing drives, data loss or corruption.
• The motherboard, memory or power supply: POST beeps, no power, a burning smell, swollen capacitors, overheating, random shutdowns, a system clock that will not stay correct.
• A laptop battery that has swollen. Stop using and charging it.
• Crashes that survive a clean reinstall. If Remove everything did not stop the blue screens, suspect hardware or firmware.

Overheating is sometimes only dust: see how to clean computer hardware safely before assuming a part has failed.

Stop early, too, when the PC holds files you have no other copy of. chkdsk /f /r and every reset option write to the drive, so a failing drive with irreplaceable data needs its files copied off first, by someone with the tools to do it. Our guide to recovering deleted files in Windows explains what you can do yourself and when a data recovery service is worth the cost.

For a business, the method is the same, but the notes matter more. Our IT support provides help by email, Monday to Friday, 9:00 to 17:00 ET, and remote fixes with a note of what was changed; remote sessions happen only with your consent. Recurring issues are traced to their cause and fixed at the root, rather than reset again next week.