Cleaning an Infected Windows PC

Cleaning an infected Windows PC requires a methodical and thorough approach to ensure that malware is fully removed and your system is secure. Here is a quick guide on how to restore your system and prevent future threats.

Disconnect from the Internet

Immediately unplug Ethernet or disable Wi-Fi. This process prevents malware from spreading or downloading more payloads.

Boot into Safe Mode with Networking

Press Shift + Restart > Troubleshoot > Advanced Options > Startup Settings > Restart > Press F5. Safe Mode loads only essential drivers, making it easier to remove malware.

Use System File Checker

Open Command Prompt as Administrator and run the sfc /scannow command. This checks and repairs corrupted or altered system files.

sfc /scannow        

Run a Malware Scan

For deep infections, use Microsoft Defender Offline Scan:

• Go to: Settings > Privacy & Security > Windows Security > Virus & Threat Protection > Scan options
• Select Microsoft Defender Offline scan and restart.

Use Windows Defender or a trusted third-party antivirus. For deeper infections, run an offline scan using Windows Security or bootable antivirus tools.

Delete Temporary Files

Press Windows + R, type temp, %temp%, and prefetch one at a time and delete all files inside. This process can help speed up scanning and may remove malicious scripts.

Check Startup Items and Services

• Run msconfig or use Task Manager > Startup tab.
• Disable suspicious or unknown entries.

Check Browsers for Malware Add-ons

• Remove suspicious browser extensions.
• Reset browser settings (Chrome/Edge/Firefox) to default.

Update Windows and All Software

• Make sure all patches and updates are applied.
• Update antivirus and browser software to latest versions.

Change All Passwords

• Especially after removing malware. Prioritize email, banking, social media, and system accounts. Use a password manager if needed. Bitwarden and LastPass are popular password managers. Ensure to enable either extension with your internet browser(s).

Backup Important Data (If Not Done Already)

• After confirming the PC is clean, back up critical data to an external drive or cloud storage.

Last Resort: Full Reset or Reinstall Windows

If the infection is too deep or you suspect rootkits or system file corruption:

• Reset this PC: Settings > System > Recovery > Reset this PC.
• Or do a clean install using a USB drive with the Media Creation Tool.

Final Thoughts

This step-by-step guide shows a structure approach that includes safe mode diagnostics, thorough malware scans, system checks, and ongoing security best practices. For novice users and office staff, please contact your IT team for support.

Disclaimer:

The information provided in this article is intended for general educational and informational purposes only. While every effort has been made to ensure the accuracy and effectiveness of the steps outlined, the author makes no guarantees regarding the results or potential consequences of following this guide. Performing malware removal or system modifications may carry risks, including data loss or system instability. It is strongly recommended that users back up important data before proceeding and consult with a qualified IT professional when in doubt. The author is not responsible for any damage, data loss, or issues arising from the use or misuse of the information provided.

About the Author

Nicholas Mutsaerts is an experienced IT Support Specialist focused on Windows, macOS, and Linux environments, and tier 2 help desk support. Passionate about empowering users through clear guidance and technical training.