my iomega 250 external hard drive after 3 years is not working. in device managers, usb, it is recognized as a mass storage device and indicates that device is working properly. However, when I go into disk management it is not there. I checked the plugs and the power plug is missing a prong, but the light is still has green as ever, could that be the problem or what else? I have data that is not replacable. I tried plugging it into Windows Vista, that did not recognize it either, could I have screwed it up by plugging into Vista. Please help.