well bud..it will b wrong to jump to conclusion thats its gone....1st check if the data Cable is properly inserted .....2nd chk for the Jumper setting(chk ur HDD's front side Or go Here ).....if there is conflict in the jumper setting..then also it can happen.....and lastly chk for any physical damage....may b ur FAT has gone bad (but it wont show in Bios ...hmm) ...i wud suggest after going thru 1st n 2nd suggesion if it does not work....get it checked by proffesionals.for accurate results....