I've had to resurrect a few hard drives. Not fun.

It's been a while, but I had luck with Testdisk to make it boot or see it in windows. Then used Recover My Files to pull off the data.
I've also used Active@Undelete with luck too.

Sounds like you're lucky and it's not your boot drive that failed, at least you can still run an OS with software to revive the external HD... Hopefully it's not hardware that failed and you can still force a read.

Good Luck.