Did you name the computer the same?
This happened to me.. I reformatted with one of the methods that claimed it *shouldn't* delete files. Reformatted, restarted, and fresh computer... minus all the files we needed. I mean wedding invitations (I designed them and have been printing them), MP3s, address lists, my fiancee and I's resumes, my design portfolio, ect.
I then found that some of the programs were still installed, so I snooped around a bit, and found that if I went into the windows folder, everything was there, just "my documents" become "my documents.LAPTOP" and there was also a folder "my documents.XXXX". I had renamed the computer "LAPTOP" so everything was stored to a different, umm, profile, if you will. You can try that, other than that, try plugging the drive into a good computer.