Can you try to open up the catalog from the backup folder of the Lightroom catalog what happens.
I'm afraid I've been rather bad and I honestly haven't backed up the catalog.
Lets try this.
Create a new catalog
- Choose File > New Catalog.
Choose the location where you want to create the new catalog.
Once the new catalog is created then we will import from the old catalog which we are not able to open. Hope this worksChoose File > Import From Another Catalog
Navigate to the catalog you want to import and click Open
Sadly that didn't work. "Cannot import from catalog. Does not seem to be a valid catalog" the box says (well at least loosely translated from Swedish).