I HAVE A SEAGATE 200GB

Question

I HAVE A SEAGATE 200GB HARD DRIVE WITH EXTERNAL ENCLOSURE, THE PROBLEM I CAN NOT LOAD IT OR MY LAPTOP VISTA OR XP WILL NOT RECOGNIZED MY HARD DRIVE ? WHY? WHAT CAN I DO TO MAKE IT FUNCTIONAL??? i brought it last March 2006 and it is loaded in a desktop at that time it is working perfectly not it will not functionNANCY CHOEMAIL: [e-mail]