Have gateway computer with windows vista , 18 months old, turned on computer and it doesn't read the HD, tried another HD and the same thing happened, tried changing the wires and still doesn't work, tried booting from a disk but it doesn't work cause the HD can't be found. Any sugestions. Thank you.. . John

Are you seeing the disk in BIO's ? Does it recognise a usb disk ?

My daughter had a Compaq that was doing this same thing. After diagnosing and going through steps, turns out the HD is dead.

My daughter had a Compaq that was doing this same thing. After diagnosing and going through steps, turns out the HD is dead.

That's a possibility also. But the OP mentioned trying another HD and different cables.

If the computer isn't seeing it in the first place then that is a major problem. It could be a driver etc. Not knowing what type of drives they are IDE vs SATA. The bios could be corrupt. The only other way to tell is if it reads either usb or cd boot disks.