Probably the best solution is to restore your WP database, if you have backup. If not, ask your hosting provider to do that, if you are on shared on VPS hosting, they should make full backup of your account and database every 1-2 days (even without your knowing).
Because you exceeded disk quota, maybe something else is not written to the disk, or partly, so my best recommendation is to ask your hosting provider to restore your database, maybe even better your full account, on shared and VPS systems it will be quickly. If you are on dedi server, than you probably have your backup and you know how to do that yourself.