Today I don't seem to be able to open my lightroom catalogue, nor my previous backup - only a backup from last week, meaning I lose around 500 selected and pre-edited photos... It does not seem to be able to restore. I have copied it to a different drive, and still have the same issues.
Are you using MacOS Monterey and did you update it to the latest version recently? If so, try this: Go to MacOS 'System Settings - Security & Privacy' and add Lightroom Classic to "Full Disk Access". Click on the lock icon to unlock the settings, then click on the plus icon to add Lightroom Classic if it isn't already listed. If it is listed, then just enable the checkbox.
So despite the messages saying LR would attempt to fix the issue, it cannot open the catalog? If so, and if your only recourse is a backup, that's what you'll need to work on. You really want to be backing up more often but that's water under the bridge. In some rare cases, Adobe engineering may be able to fix a corrupted catalog but the users here who volunteer cannot do so.
Get a good backup schema that backs up everything on your Mac (not just the catalog) automatically and daily. An inexpensive product is SuperDuper.
Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"