Unfortunately, my command prompt got stuck after the "clean" command and seemed it was never going to end so I manually closed the command prompt window. Next time I rebooted the computer I noticed that the external hard disk had stopped showing up in My Computers.
Is there any way I can get it back or does it seem damaged beyond repair?
I am using Windows 8.
Update: I see the drive mentioned under Disk drives in Device Manager only when I "show hidden devices".