I had the exact same problem. Here's what I did to initialize the disk:
-- Right click on My Computer, choose Manage
-- Go to the Disk Management section (under Storage)
-- Your disk should be listed in the lower section; it will say Disk 0/1/2 (etc.) and say Not Initialized
-- Right click on the GREY portion of that line (where it has the Disk icon), not the white part (where I was clicking before I realized my error)
-- Choose Initalize. It takes but a moment for it to mount the drive.
-- You can now right-click on the white area (to the right of the grey area you just clicked on) to choose a formatting option and make it ready for use.
Finally, if that doesn't work, it is more likely that the hardware really has failed. There's not a lot you can do in that event, unless you have a Clean Room in your basement (doesn't everyone?). At that point, you should work on an RMA (if under warranty) or replacement purchase (if not).
I had the same issue