Suddenly Windows Defender Won't Open

Variety1969 said:

Hi there:

For some reason, when I tried to use Windows Defender today I get the following message:

"This application is turned off by group policy. To allow this application to run, contact your security administrator to enable the program via group policy"

WTF? I haven't done anything or changed anything. All I did was turn on my PC.

I tried to open group policy via run gpedit.msc but it says file is not file is found....

Please help!!!! Lynn

Hi Lynn and welcome to Tenforums.
If you have Windows 10 HOME, Group Policy Editor is not available to you (only W10 Pro).

Do you have another AV running on the system? If so, many times that will turn Windows Defender off, so they don't conflict.

If no other AV, try booting into safe mode and see if you can run it there.
Boot into Safe Mode on Windows 10 - Windows 10 Performance Maintenance Tutorials

If so, set it to run an offline scan.
Windows Defender Offline Scan in Windows 10 - Windows 10 Security System Tutorials

If not, please try downloading and running ADWCleaner.
Downloads - AdwCleaner - ToolsLib

If it finds anything, please post the logs, found in C:\AdwCleaner\AdwCleaner[S1].txt and C:\AdwCleaner\AdwCleaner[C1].txt

If ADWCleaner finds nothing, open an admin Command Prompt or admin PowerShell and enter:

Code:

sfc /scannow

The result we're looking for is "No integrity violations found".