Nothing hurts more than losing an important file to your own stupidity. Without going into too much detail--I know the feeling well. However, there's no analgesic like a good recovery program and Active@ File Recovery (various pricing, see below) is Alka-Seltzer personified.
I've used Active@ File Recovery on several occasions. It's recovered everything possible, every time. Sometimes if a file or portions of a file have been overwritten, there's nothing you can do...but if you haven't written to the hard drive and there are no bad sectors, Active@ File Recovery can get it back. Even if you've repartitioned a couple of times, the program's sector-by-sector superscan will find what you lost and rate its chance for successful recovery. Recoverable files are listed by location and by common file types so you can quickly find that PDF presentation you really need.
My only caveat is that the language and concepts used throughout the program are pretty technical, so neophytes might want to ask for some help from a techie friend. All told, Active@ File Recovery is on par with Ontrack's EasyRecovery Professional in its effectiveness. Download the Active@ File Recovery demo and see if it finds the data you need; if the size of the file you're trying to recover is less than 64KB, the demo will even restore it.
For non-corporate users, Active@ File Recovery Standard is $35 and the Professional version, which adds partition recovery, costs $45. The Enterprise version, a downloadable bootable CD, is $99 for users of any ilk.