This wouldn't happen in normal usage, but it's possible your disk was corrupted and the database was damaged. You can try recovering from the last automatic backup.
Do you have your database in the standard location or somewhere else (e.g., a cloud storage folder)?
Upgrade Storage
Do you have your database in the standard location or somewhere else (e.g., a cloud storage folder)?
You can also provide the info from Locating Missing Zotero Data, which might give a clue as to what happened.