I ran an sfc /scannow and tried to replace corrupted files in the fr-FR folder, but it says access denied.

[basswinding]

I’ve also tried doing this in safe mode and using other methods, but nothing has worked. Can you help me? Thank you!

 

[Bighorn]

Check this page, usually DISM is ran when SFC has issues:

DISM Overview

DISM overview

learn.microsoft.com