Computer no longer recognising my hard drive??

Hello,I have had this Hard drive for two years now(Seagate FreeAgent GoFlex Media 1TB). It is used in conjunction with my Apple Macbook Pro.

I have never had any problems with the HD until today. It was working fine and I plugged it back into my computer to use it again and it wouldn't register on the screen. A pop up message stated that the disk you inserted was not readable by this computer.

The pop up leaves you three options, eject, ignore or initialise, upon clicking initialise you can then verify the disk and try and repair the problems. But as it is repairing it stops and states that Main boot region is invalid, and goes on to state that the alternate boot region is invalid.

I have also tried the HD on another computer which gave the same response.

Can you tell me the prognosis and the best course of action to take from here on out? Is thee anyway I can access the information stored on this hard drive?

Many Thanks

Scott