PC is locked due to Window Defender reporting trojan spyware

If the message is in a web browser and shows a warning that the PC is locked because of trojan spyware, that is commonly a scam page rather than Windows Defender actually locking the PC.

Try this first:

1. Press Ctrl + Shift + Esc to open Task Manager.
2. On the Processes tab, find the web browser that is showing the alert, such as Microsoft Edge.
3. Select it and choose End task.
4. Reopen the browser, and if prompted to restore tabs, choose No so the scam page does not reopen.

After closing it, run a malware scan:

1. Open Start > Settings > Update & Security > Windows Security > Virus & threat protection.
2. Check Protection history for the alert details:
   • Threat blocked means Defender already blocked and removed the threat.
   • Remediation incomplete means more cleanup steps are needed from the alert card.
3. Under Current threats, select Scan options.
4. Run Windows Defender Offline scan. This is useful if malware keeps returning or hides while Windows is running.

Important:

• Save work before an offline scan because the PC will restart.
• Do not pay money or call any phone number shown in a pop-up warning.
• If the same malware keeps coming back, avoid the site or download source that delivered it.

If there is a real ransomware-style infection, fully clean the PC with Windows Security before trying to recover files.

References:

• Troubleshoot problems with detecting and removing malware
• Protection History in the Windows Security App
• Protect your PC from ransomware
• My computer has been locked up by Microsoft Windows defender! It says my computer has picked up a Trojan-type spyware! I can’t do anything with it! Can you please help me? - Microsoft Q&A
• Unwanted pop up security alert claiming to be Microsoft - Microsoft Q&A