Originally posted by electricdawn:

Do you have backups? If not you‘re probably hosed, as the game probably has overwritten its internal backup already.

The three most import things about computing:
1. backups
2. backups
3. backups

Edit: Do you have Steam’s cloud save on? You might be able to restore your game from there. Not sure how it works, though. Worth a try.

Can't believe you didn't mention the most important thing:

Backups.