I hate to be the bearer of bad news, but you're likely out of luck. We almost never hear of anyone recovering image data from a damaged PSD.
1. Set up backups.
2. Get in the habit of saving your master file in several different locations as you work on it.
3. Consider upgrading to Photoshop CS6, which auto-saves your work in the background. I'm not sure whether it would have recovered the data in your particular case, but it's possible.
4. Don't feel bad - go back and do the image again, and I'll bet it comes out even better in less time.