BuddyPress.org

My 10c worth – it also may be that your database is corrupted – perhaps a plugin that hasn’t tidied up correctly.

I suggested earlier that you revert to a previously backed up database (ideally from a known working version) and system.

If you are not able to do this – as @hnla suggests, you should look at hiring a developer who’ll be able to look directly at your database and files, and dedicate the time you need to find a fix.