There may be ways of retrieving the data, but you coul try a couple of other things just before giving up on the drive.
1. Do you have an alternative USB or Firewire cable you could try (depending how it's connected to your Mac).
2. Does the WD external disk allow connections via both Firewire and USB (mine does)?. If so, if connected via USB try connecting using Firewire instead - and vice versa.
3. Do you have any other devices - USB stick, Printers, etc - that you could plug into where the WD is normally connected. Do they still work? If they do, it would suggest that the ports are OK and the issue is with the WD.
If all this points to confirming the WD has failed I guess you need to get a replacement drive and start over with TIme Machine.