Please try this:
- Drag your whole Sims 4 folder from Document > Electronic Arts to your desktop.
- Verify Files in Steam
- Launch Sims 4. You should get no list of mods on launch, and you should have no option to load a previous save.
If that works, start putting old content back:
- Exit and copy files out of your old Saves folder into the new Saves folder. Important: Don't just copy the old folder! You want to use the newly created folders.
- Launch Sims 4 and use Load to select an older save to test.
If that works:
- Copy your old Tray files (this is your Library), Screenshots and Videos files.
- To test mods, copy the files into the new folder in batches with any mods they depend on (injectors and core mods, for example). Don't copy your old Resource.cfg file. If you delete any mods from the new folder, delete the file called localthumbcache. Check the instructions on 50-50 testing here: https://forums.ea.com/discussions/the-sims-4-mods-and-custom-content-en/info-how-to-use-mods-and-cc/9360653/replies/9360660
