One reason an external HD will crash is overheating.
Sometimes if you turn them off and disconnect for a bit, they will work again.
If not you can get your files back with file scavenger or similar program.

Mine crashed and all I could see was it had reformatted to RAW (whatever that is) but I used a file scavenger like program and got everything back.
Of course you need a big drive to save it back to.
Then I reformated to FAT again and it works okay.

BUt I now backup important a
stuff to CD ubtil I get a DVD burner.

Let me introduce you to my multiple personalities. :)
     BluEcho...Faery_Light...Faery_Souls.