My WD External Harddrive 2tb won't open!

It worked for me on an internal.

I had a drive die on me.  If the drive was connected via SATA, Windows wouldn’t boot – it would just hang at the splash screen.  Disconnecting the drive allowed Windows to boot normally.  DLG wouldn’t run on it from DOS – the drive would disappear as soon as DLG tried to look at it.

I booted with a SystemRescue CD (as suggested by another helpful person around here).  The drive was visible/accessible in 'nix – sometimes.

I managed to copy the data off it (in many sessions… the drive would work for a while in 'nix and then up and disappear while files were being copied – took about a week to get everything off it).

Glad it worked for you too.