Uh, Oh.
Chances are that the files are still there. But getting them back may be a problem.
Try booting from this floppy (Run the program to create the floppy) and running "pr.exe" at the prompt. Try the option to scan the drive for partitions. See if it can recover anything.
http://users.adelphia.net/~abraxas/dl/APR.exe
Recovery software will need a defined partition before it can even search. But do as little as possible to that drive to avoid erasing anything. In other words, try one thing at a time and then use this program to see what it can recover before trying something else since each step is capable of permanently erasing the files.
http://www.pcinspector.de/file_recovery/welcome.htm
If all else fails, use Disk Management to create a new partition in the exact same place as the old one. Format it, but be sure to do a "Quick" format if the option is available to avoid erasing any surviving files. Then try the PCI recovery utility again.
Here is another file recovery program that you can try. See if either will scan without a format first, but I think a format will be necessary. With this program (Restoration), click "Others" and "Scan All Clusters".
http://www.snapfiles.com/get/restoration.html