Start with the basics before you dig deeper

Most PC problems have a straightforward fix: restart the machine, check your cables, make sure nothing is blocking the vents, and verify that Windows updates have finished installing. A restart clears temporary files and resets connections that may have stalled. If your PC is slow, frozen, or won't start, try a full shutdown (not sleep mode) and a cold restart before moving to anything else.

Check the physical connections next. Make sure the power cable is fully seated in both the wall outlet and the back of your PC. If you use external monitors, keyboards, or drives, disconnect them one at a time and restart—a faulty USB device can prevent Windows from loading. Look at the back and sides of the case for dust buildup around the fan vents; if you see thick dust, use a can of compressed air to clear it, holding the can upright and spraying in short bursts.

If the PC still has the same problem after a restart and a cable check, move to the next step. If it works normally after the restart, you are done—the issue was temporary.

Key Takeaways

  • Restart your PC completely, check all cables, and clear dust from vents before troubleshooting anything else.
  • Use Windows built-in tools like Task Manager, Device Manager, and Disk Cleanup to diagnose and fix common slowness and error problems.
  • Run a full antivirus scan if your PC is slow, shows unexpected ads, or opens programs on its own.
  • If your PC will not start at all, try booting into Safe Mode or using Windows Startup Repair before assuming the hard drive has failed.
  • Back up your files to an external drive or cloud storage before attempting major fixes like a Windows reinstall.

Use Task Manager to find what is slowing your PC

If your PC is slow or freezes often, open Task Manager by pressing Ctrl+Shift+Esc. Click the Processes tab and look at the CPU and Memory columns. If one program is using more than 50% of your CPU or most of your available memory, that program is the problem. Right-click it and select End Task.

If no single program stands out but your PC is still slow, click the Startup tab. Programs listed there run automatically when Windows starts. Disable any you do not use regularly by right-clicking and selecting Disable. Restart your PC and check whether it feels faster. You can always re-enable them later if you need them.

If Task Manager shows your disk usage at 100% constantly, your hard drive may be failing or Windows is running a background task. Wait a few minutes—Windows Update or a virus scan may be running. If the disk stays at 100% for more than 10 minutes, restart your PC and check again. If it happens repeatedly, move to the antivirus section below.

Check Device Manager for hardware errors and missing drivers

Open Device Manager by right-clicking the Start button and selecting Device Manager. Look for any device with a yellow exclamation mark or a red X. These indicate a driver problem or a hardware failure. Right-click the device and select Update Driver, then choose Search automatically for updated driver software. Windows will search online and install the latest version if one is available.

If updating the driver does not remove the warning, right-click the device again and select Uninstall Device. Restart your PC—Windows will automatically reinstall the driver. If the warning returns after restart, the hardware itself may be failing and you should note which device it is.

Pay special attention to your network adapter and graphics card. If your internet keeps dropping, update the network adapter driver. If games or video playback stutter, update your graphics driver. You can also visit the manufacturer's website directly (Intel, NVIDIA, AMD, Realtek) and read the latest driver from there, which is sometimes newer than what Windows finds automatically.

Run antivirus scans and remove malware

Windows Defender is built into Windows 10 and 11 and is sufficient for most users. Open Windows Security by clicking the shield icon in your system tray or searching for Windows Security in the Start menu. Click Virus & threat protection, then click Scan options. Select Full scan and click Scan now. A full scan takes 30 minutes to several hours depending on how much data you have, so start it when you do not need your PC.

If you suspect malware (your PC is slow, you see ads you did not click, programs open on their own, or your browser homepage changed), run the scan before doing anything else. Malware often hides in startup programs and background processes, which is why Task Manager alone will not find it.

If Windows Defender finds threats, it will quarantine them automatically. If your PC still has problems after a full scan and restart, read Malwarebytes (the free version is adequate) and run a scan with that as well. Some malware evades one scanner but not another. Restart after Malwarebytes finishes.

Free up disk space with Disk Cleanup and storage management

If your PC is slow or you see a storage full warning, you need to delete unnecessary files. Open Settings by pressing Windows key + I. Go to System, then Storage. You will see how much space each category (apps, photos, videos, temporary files) is using. Click Temporary files and select what you want to delete—Windows will suggest deleting old downloads, the recycle bin, and temporary installation files. Click Remove files.

If you still need more space, go back to Storage and click Apps & features. Look for programs you no longer use and click them, then Uninstall. Be cautious about what you remove—do not uninstall anything you are unsure about. If you have large video or photo files you do not need, move them to an external drive or cloud storage (Google Drive, OneDrive, or Dropbox) and delete the local copies.

Windows also stores old versions of files in a folder called WinSxS that can grow very large. Do not manually delete from this folder—instead, use Disk Cleanup. Search for Disk Cleanup in the Start menu, select your C: drive, and click Clean up system files. This removes old Windows installation files safely.

Boot into Safe Mode if Windows will not start normally

If your PC shows a black screen, gets stuck on the Windows logo, or crashes when ready after startup, try Safe Mode. Restart your PC and hold down the F8 key repeatedly as it starts (on some newer PCs, hold Shift while clicking Restart from the login screen). Select Safe Mode with Networking from the menu that appears.

Safe Mode loads Windows with only essential drivers and services, which helps you determine whether a recently installed program or driver is causing the problem. If your PC works fine in Safe Mode, a third-party program is the culprit. Restart normally, open Task Manager, go to the Startup tab, and disable programs one at a time until the problem stops. Then uninstall the program that was causing it.

If your PC still crashes in Safe Mode, the problem is likely Windows itself or your hard drive. Try Windows Startup Repair: restart your PC and hold Shift while clicking Restart. Select Troubleshoot, then Reset this PC. Choose Keep my files if you want to preserve your documents, or Remove everything if you want a clean Windows installation. This will reinstall Windows while keeping your personal files (if you choose that option).

Back up your files before attempting major repairs

Before you reinstall Windows, replace a hard drive, or make any major change, back up your important files. Connect an external hard drive or USB drive to your PC. Open File Explorer, navigate to your Documents, Pictures, and Downloads folders, and copy them to the external drive. You can also use cloud storage—OneDrive, Google Drive, and Dropbox all offer free plans with enough space for most personal files.

If your PC will not start at all, you may need to remove the hard drive and connect it to another PC using a USB adapter to retrieve your files. This is a job for a local repair shop if you are not comfortable opening your PC case.

Once your files are backed up, you can proceed with a Windows reinstall or hardware replacement without fear of losing your data. After the repair is complete, copy your files back to the PC.

When to call a professional

If your PC makes grinding or clicking noises from inside the case, the hard drive is likely failing and needs replacement. This requires opening the case and is best left to a repair technician. If you see error messages about a hard drive failure, back up your files when ready and take the PC to a shop.

If your PC overheats (shuts down after a few minutes of use, or the case is too hot to touch), the cooling system may be blocked or the thermal paste on the CPU may have dried out. This also requires opening the case. If you have already cleaned the vents and the problem persists, a professional should look at it.

If you have tried all the steps above and your PC still has the same problem, or if you are uncomfortable opening your PC case or reinstalling Windows, a local computer repair shop can diagnose the issue for a fee. Bring a list of what you have already tried—it saves them time and saves you money.

Frequently Asked Questions

What is the difference between restarting and shutting down?

Restarting closes all programs and reboots Windows, which clears temporary files and resets connections. Shutting down closes Windows completely and powers off the PC. For troubleshooting, always do a full shutdown and then power back on—do not use the restart option. Sleep mode does neither and will not fix most problems.

Is it safe to open my PC case to clean the dust?

Yes, if you unplug the power cable first and touch a metal part of the case to discharge static electricity before touching components. Use a can of compressed air held upright, and spray in short bursts. Do not touch the circuit boards or use a vacuum cleaner, which can create static. If you are uncomfortable doing this, a repair shop can clean it for under $50.

Will reinstalling Windows delete my files?

Only if you choose Remove everything during the reinstall process. If you select Keep my files, your Documents, Pictures, Downloads, and Desktop folders will remain. However, programs will be uninstalled and you will need to reinstall them. Always back up your files before reinstalling Windows, just in case.

How do I know if my hard drive is failing?

Listen for grinding, clicking, or beeping sounds from inside the case. Watch for error messages about bad sectors or hard drive failure. If your PC is very slow when opening files or programs, or if files become corrupted, the hard drive may be failing. Back up your files when ready and have a technician check it.

Can I fix a virus by myself?

Yes, for most common malware. Run a full antivirus scan with Windows Defender and Malwarebytes, then restart. If the problem persists after two full scans, the malware may be advanced and a repair shop may need to use specialized tools. Do not pay for antivirus software online—legitimate tools like Windows Defender and Malwarebytes are free.