Have a look at http://www.google.com/search?q=unformat+ntfs
This is assuming you use Windows XP or Windows 2000 and the default NTFS filesystem.

If your filesystem is FAT, replace ntfs by fat in the above search.

I don't have experience with any of the programs or services myself. I never accidentally formatted a hard drive, in fact, AND I do have backups.

Kees