It’s been doing that for the past 25 years. Run the DB out of space, DB gods become angry.
There’s a “fwconsole database repairall” commnd that you can try, but if the DB isn’t restarting, it might not be enough. Remove the /var/lib/mysql/mysql.sock file from the system and try again. You may also need to make sure that the /var/lib/mysql directory is intact.
You’re going to have to deep-dive into the MySQL world to get back to where you need to be. A lot depends on what the error actually is, which you’re going to get from the /var/log/mysql/*err file. After looking at that, see if you can get it back from that error.