Windows Defender won't delete or restore quarantined threat

Windows Defender has quarantined two threats on my PC recently: one is an infected executable on a network share (which was put there deliberately and which someone needs), the other is a simple "potentially unwanted app" from a bundle installer I downloaded for FileZilla.

In Defender's Protection History, when I click on "Restore" or "Remove" for one threat, I get a UAC prompt, then nothing happens when I confirm. After accepting once, I don't get other UAC prompts, but further commands don't do anything either.

The Windows Security task bar icon keeps warning me of the bundle installer, even though I can't remove it.

Why can't I act on quarantined threats, and how can I fix this?

Solution 1:

Let's fix the issue from Command prompt.

First open Command Prompt as Administrator. Then run cd "%ProgramFiles%\Windows Defender". Now run MpCmdRun.exe -restore -listall and you will get a list of quarantined files. Now choose the file you want to restore and run MpCmdRun.exe -restore -name "Filename" where "Filename" is the file's name you want to restore.

If it does not work, temporarily disable File checking by Windows Security > App & browser control > Check apps and files option set to Off and restore it now. Now again you can turn it on.

Hope that helps