Sounds like either your drive enclosure or the drive itself has failed.
If the enclosure has failed and you don't have any crucial files on it that you don't already have elsewhere, contact Iomega for a warranty replacement.
If the enclosure has failed and you DO have important files on it, try having your local PC
shop move the hard drive into a new enclosure, if that works you're done, buy the new enclosure.
If the above suggestion fails, your drive is damaged and you will need a pro to help get back your files. If this is the case, reply back with you location(Country, State and City) and I will pass along recommendations for your neck of the woods.
Hope this helps FixYa,