If you haven't launched Plant Tycoon again once you discovered the problem, you should be able to use the procedure at the bottom of this post to recover the backup file that the game automatically creates for you. Unfortunately, many people react in disbelief when they see that their game is gone, and launch Plant Tycoon repeatedly to try to figure out what happened. That's the *worst* thing you can do when you discover a problem with any software, since it usually destroys valuable files in the process.