Re-install deleted categories help!!

I accidentally deleted all my categories and sub-categories. I was trying to just delete the parent category and didn't realize that all the sub categories would go with it. I have back-ups, but only want to recover the categories. Please help and let me know where in the root directory it would be located to do this. I'm using ftp for file transfer. Just need to know which files and if this is even possible.
Thanks,
Misty

Only possible if you have a database backup

If you havent done one, check with your hosts as they may periodically backup your DB for you