I'm sorry you've lost it all, that's very unfortunate. I know it's not much comfort now, but in the future I strongly suggest saving revisions of your in-progress scene files, rather than simply saving changes over and over again to the same file. For example save "hills1.tgd" then "hills2.tgd", etc. That way even if one gets corrupted, you can step back to the previous one and you have only lost whatever you have done since the last revision. I would make one revision per day at the least.
- Oshyan