Assume Windows of some sort...? I use a prog called Easy Recovery Professional v6. Load prog onto a working version of Windows (W2K, XP), then attach your mistakenly formatted drive to that computer either as a slave or to the second IDE i/face. Run Easy Recovery and hopefully you'll be able to restore what you need. You'll need some hard disk space on the working (Windows) drive to recover your files to.
Good luck.
ROGER.