Are you not using Steam? By default it uses Steam Cloud for your saves. Since it doesn't save as you play, it only saves at checkpoints (When you complete tasks) I can't see how it corrupted your save; unless you're saving locally and the computer crashed as it was saving.
Are you using Windows 7 or 8? If so, and you're playing OFFLINE (no Steam Cloud Save) you could located the save game location, right click and choose restore Previous Versions.
Hope you can recover!
But, being one who restarted the game 3 times, It's not that big of a deal to restart. It is a fun game.
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