Hello,
Thank you for posting in Q&A forum.
1-877-891-5944 is not an official security support phone number provided by Microsoft. This situation is usually a form of fraud known as technical support fraud. Scammers often use fake phone numbers and pop-up warnings to deceive users and claim to need to pay fees or provide remote access to solve problems.
If your computer experiences a situation similar to Windows Defender lock, it is likely a form of malware or fraudulent activity. I suggest you follow the following steps to address this issue:
Force computer shutdown: If your computer cannot respond to any commands, you can try holding down the power button to force the computer to shut down.
Safe mode startup: After starting the computer, try to enter safe mode. Safe mode will start the computer and only load necessary drivers and system services, which can help you identify and solve problems.
Running antivirus software: In safe mode, run reliable antivirus software, conduct a comprehensive system scan, and remove any potential malicious software.
Check system recovery: If the above steps cannot solve the problem, you can consider using system restore or recovery functions to restore the system to its previous normal operating state.
In summary, 1-877-891-5944 is not Microsoft's official security support phone number. Please do not provide any personal information or pay any fees to this number.
Hope this answer can help you well.
Best regards，
Jill Zhou
