HDD suddenly not mounting.

Hi guys. I have a little bit of a problem. My seagate 1TB HD today has decided not to mount.
I have tried a brand new cable, different USB ports, nothing.

The HDD does NOT show up in disk utility and is nowhere to be found. The HDD lights up when it is plugged in, but my macbook pro does not respond. I need to have his resolved as soon as. Im thinking its an issue with the HDD, there is so much important data on that thing. Does anyone have any suggestions? and if it is the HDD, does anyone know what i should do now in terms of getting the data off it? It does not respond on a PC either.
Dan

Welcome to the Mac-Forums.

It does sound like your Seagate drive may be dead. If the drive can not be seen by Disk Utility, it is very unlikely any kind of recovery software will be effective. What you can try... is remove the case with the electronics and expose the bare drive. Then purchase an adapter and attach the bare drive to your Mac to see if you can read the data from it. Many times the electronics in the drive will fail but the drive itself is OK. Of course removing the drive from the case voids the warranty but I'm sure you would rather have your data than just swap the drive for a new one from Seagate.

Just to be more carefully clear, what chscag means is to open the external case that has the interface hardware and maybe a power supply and replace that with an adapter that lets you attach it to the Mac. This is the kind of adapter we mean. The electronics card actually ON the drive has to stay on the drive, it's carefully tuned to the hardware of the internals of the drive and replacing THAT is a job for an expert. Once the drive is free from the external case and connected by the adapter you can see if it is working or not. If it isn't working then, the cost to recover is going to go up significantly.

Important data not backed up ... If the suggestion above doesn't work you are looking at a couple grand to fix this. Hopefully, lesson learned.

Something I hadn't noticed until now. When the HDD is plugged into the Mac, it beeps about 5 times quite quietly and DOES NOT spin up. It remains silent. The light still remains on, power is getting to the drive. My question. Someone has suggested the universal drive adapter, will this work if the HDD is failing to spin up? I don't know how it works. Dan

Afraid she be dead and avoid Seagate. Go with a WD replacement.

If it has power and it's not spinning, it's dead. Bu the light being on does NOT mean the drive is getting power, just that the light is on. The drive adapter I mentioned in post 3 comes with a power supply. IF, and there is no way to really know, the power supply in your external enclosure has died and is not providing power to the drive motor, then it is possible the adapter will be able to get it spinning. However, I must be honest, 90%+ of the time the drive doesn't spin is because the drive has died. BUT, if your data is that critical to you, getting the adapter will give you one last shot at getting it going again long enough to recover your data. No guarantees, and it is a bit of a longshot.