As someone who has run into the same problem, and has lost all of a customers data, I have developed a "better safe than sorry" method of data recovery from a non-bootable hard drive.
Anything you do that can write to the drive, can wipe out valuable data. READ ONLY is what needs to be done, and the safest way to do that is to remove the hard drive from its parent PC, and slave it to another PC where it can be read, (read only) and the data copied off of that HD and saved to the main drive on the PC. Then it can be safely burned to DVD's for safe keeping.
I've had to do this for my customers, more times than I like.
Then I run CHKDSK /f /r on the slaved drive, from my main drive and OS, and more times than not, that restores the drive to BOOTABLE condition.
If you were nearby, I'd say "bring in over here and I'll fix it for you".
But before you permanently overwrite your data files, you might want to get that little PC to a professional PC Tech that can possibly save your data for you.
Good Luck!