I have a 500gb Seagate Freeagent Desktop external hardrive, which is not being read on any computers. I have tried reading it on three differecnt computers with no luck. The device cannot be found anywhere, including device manager and disk manager. I need to access the files on it to the drive cannot be wiped. There is power to the drive as the light is on and I can physically feel the disc moving inside the case. Thanks in advance for any help.