I am afraid you have only 2 options, both of them are very easy.
1. Reinstall the whole system.
2. Faulty hdd - needs to be RMAd.
easy to check, get linux live cd, start up from live cd and see if you can see the hdd that way, if you can see it and browse it, then its just the system, if not, then u gotta send the hdd for repair.
Yeah thanks i'll give this a go...