i have a seagate freeagent external hard drive and when i just switched it on it does not light up any more and you can hear the hard drive spin up and make a grindy noise then spin down agian and it just stays in that cycle until i turn it off.
is it died as i have all my family photos and important bits on there

Also a possibility that shouldn't be ignored is that the external closure is dead or dying and the drive itself is fine.  I'd remove the drive and either connect it internally to the pc or try it in another external closure.

its powered from the mains socket so would you still say that the encloser is dying maybe and not the drive?

i have took the plastc case off but its got a metal case on inside do i need to remove this as well?

its like the WD mybook and yes to the other part

yes still under warranty. diagnostic program wont work becuase the drive does not even apper on the my computer  part of the screen

powrs up but does not light up to show  its working. its powered by the mains not usb so why would changing usb make difference fella?

ok will try if that dont work what do you recommend?

If the drive does not have the standard connections (it probably will), and you cannot determine if it is the drive or the enclosure, I would see if there are adapters that will convert the drive connections to the standard ones.  Should there be no "at home" solutions, I would call the manufacturer, state what has happened, and inquire about a way for them to copy your data to CD's and ship them to you along with the replacement drive.  I really feel that the connections will be the standard ones, and you will be able to mount the drive either internally, or in a different enclosure to determine the state of the hard drive itself.