Ovi, welcome to the forums.
From your new catalog, try the File > Import from Catalog... function. Choose the problem catalog, or a backup, and attempt to import it. You'll be offered an opportunity to choose how much of the catalog you'd like to import, try to do it in small pieces, to attempt to isolate the corrupt portions.
This isn't guaranteed, but is likely the best first approach. Wouldn't hurt to have backups of these files as you're working. Beyond that, if you've been using the save XMP metadata function, possibly some of your LR work is recoverable.
If that doesn't work, let us know. How big is your catalog, how much Lr work invested?