OneDrive has messed up my game and my mods folder

Supernova2106  Relink OneDrive, copy the Mods folder somewhere else that OneDrive doesn't sync, and then unlink again.  Do the same for your saves and Tray folders and anything else you want to keep.

For a more detailed explanation, please see the first post of this thread, particularly the "I want to get rid of OneDrive" section:

https://answers.ea.com/t5/PC/CURRENT-ISSUE-Sims-4-saves-user-content-disappearing-PC/td-p/12475370