Hi, I am Dave, I will help you with this.
When you try to access Defender, if oyu are asked if you want to allow it to make changes to your PC, select Yes, that is just a user account control setting that causes apps on your PC to ask that question.
In Defender in the Defender History section, you should be able to see a list indicating what malware was found on your PC, which would include the name and location of the file.
If not, boot your PC into Safe Mode, then in File Explorer, go to this folder and you will find any file(s) that have been quarantined.
C:\ProgramData\Microsoft\Windows Defender\Quarantine