Hi,
An OS item is a File or Folder. It is not limited to a Windows File or Folder, it can be any File or Folder.
In your situation you need to run a Complete Format Recover on the "physical" drive. In the drive selection window, you should see a 750gb (or there abouts) physical drive listed.
Follow the instructions here:
http://forums.getdata.com/computer-d...ard-drive.html
You should be able to get all your files back in about 2 hours.
You must save files to another drive. Only when you are sure that you have recovered all the data possible from this drive and are happy that all the files you have saved are ok, should you then format the problem drive and start copy data back to it.