Mods and Saves Gone

@Talia_Simss  Okay, that's a copy of your Sims 4 user data folder, not the program files.  You can prevent OneDrive from auto syncing the contents of Documents:

https://support.office.com/en-us/article/choose-which-onedrive-folders-to-sync-to-your-computer-98b8b011-8b94-419b-aa95-a14ff2415e85

Launch the game once, to make sure all your content is still present.  If it is, you can just delete the Sims 4 folder in OneDrive.  If your content isn't showing up in-game, you can replace the folder the gme is using with the one from OneDrive.  Open a File Explorer window, click on This PC in the left panel, then follow this path:

C:\Users\[your username]\Documents\Electronic Arts

Move the Sims 4 folder to the recycle bin; don't empty it yet, in case it turns out there's something in that folder you want.  Then move the Sims 4 folder from OneDrive to the Electronic Arts folder in the path above.  Open the game again, to make sure all your content is back.