If your drive has mechanically failed you are probably out of luck. There is an old trick that you can put a hard drive into the freezer overnight and then plug it in and it sometimes works. I never did this with an external hard drive, but it should still work. I've had luck with this method 2 times ever, so it's a long shot. It also only works for a short time while the drive is icy cold. So act quickly. This is only if it has mechanically failed.
If there is drive corruption the two about apps may help you pull off any data you really want. It will be a tedious task though.