Odds are the drive has failed, and there is no method of correcting this. You can either send the thing off to professional recovery services or just accept that everything on there is gone.
I was looking for a free PDF editor. I found and installed BeCyPDFMetaEdit on my external Seagate Hard Drive. After errors regarding and then telling me that manual unstallation would be required, my Vista64 Home says my external hard drive needs to be formatted. From a DOS window, I can see the infomation on the hard drive, quite a bit of stored information. Windows sees the size and used space, but if I try to explore the drive I get the "Needs to be formatted to use". I am NOT going to do that. I connected the external drive to another system running Vista32 Home and get the same errors. Can anyone tell me how to correct this without formatting my hard drive?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic