I have a simpletech external harddrive (re)drive and for a little bit it seemed to have a problem because it would eject itself randomly, and then after a while it just would not open and a pop up would say "drive is not formatted, do you want to format it now?" No matter what EVERY TIME i OPENED it i would get this message. Then finally i decided to take the loss of information and just reformat. It took 2 days and then it said there was an error and now i cant click on it at all. If i go to my computer and right click on the (re)drive and hit explore a message comes up that says "f:/ drive is not accessible error with Inpage operation. PLEASE HELPSound like it bit the dust to me. When it ejected your DISK without prompting is a good sign it went bye bye. Check your cables and see if it shows up in your BIOS. If it does show it may be more complicated. You could use your install disk to format outside of your OS.take a visit to disk management with the disk connected.

GO down to the external drive letter.

What is it listed as? any PARTITIONS?