Hard drives have a set of weakness as they have a motor to spin the platters and within the arm there is a solenoid to move the arm across the platters to then allow a very tiny set of magnetic heads to read the magnetic flux laid-out as a track (one per side times the number of platters) and one of these areas can fail and in doing so makes the drive not work.
Do you hear any noise when you first power up the drive? You should hear the spinning of the platters ramp up, then a click when the head assembly unlocks its self, followed by the sound of the head assembly seeking the inner track.
Do you hear these sounds and if not which.