Drive failed to boot up

Question

drive failed to boot up next time it was turned on have tried conncting as a slave computer recognises drive but say its 138mg when its 40gig, and there is nothing showing on the drive! have tired running Seatools for windows and all the test say there are no problems with the drive.I have in stall a nerw 250gig drive (Seagate) with NTFS file system and the problem one is a Maxtor with fat file system .