hard drive failure

Solution
Main cause - - the hard drive has failed & is no longer usable.

Other possible cause - - operator error.

If you're sure it's not operator error, test the drive with bootable diagnostic software on a CD or pen drive:

Drive Fitness Test for DOS: http://www.hgst.com/support/hard-drive-support/downloads/legacy-downloads#DFT

SeaTools for DOS: http://www.seagate.com/gb/en/support/downloads/item/seatools-dos-master/

Both will test any make of hard drive.
Main cause - - the hard drive has failed & is no longer usable.

Other possible cause - - operator error.

If you're sure it's not operator error, test the drive with bootable diagnostic software on a CD or pen drive:

Drive Fitness Test for DOS: http://www.hgst.com/support/hard-drive-support/downloads/legacy-downloads#DFT

SeaTools for DOS: http://www.seagate.com/gb/en/support/downloads/item/seatools-dos-master/

Both will test any make of hard drive.
 
Solution