I'm assuming this is in a USB external enclosure. If you can get it to run internally then the problem may be with the USB enclosure.
I have a maxtor 3100 80bg external, working fine one day and now computer (xp) will not recognize it. Green light is one but no sound from drive, tried drive in another computer still nothing. Some blogs said try a hard drive enclosure any thoughts. In the past the drive worked would warm and i could hear a hum now nothing but the green light.