nothing is impossible. actually it would be fairly easy to use an adapter and use the DVD/CDrw's channel to house the HDD, both are ATA devises so...
that solution would force you to live without the DVD/CDrw. but you would get a working HDD on the laptop.

just a thought, have you checked that the "ribbon" is fully inserted into the socket on the other end?
I am talking about the ribbon sometimes atached to the hdd conector, that may get broken or dislodged, it is very fragile and the socket just "clamps" it in place.
hmm, here you have a link showing the type of cable and how tu detach/atach it.
http://www.massena.com/darrin/pilot/luiz/item9.htm
it is not 100% same but it was what i could find, principle is same.