External Hard Drive No Longer Recognized

Hello,

Two months ago I bout a 500 gig Western Digital My Book Home Edition external hard drive. I had been using it successfully with my PowerBook G4 laptop until this morning. I had unplugged the hard drive from my laptop while I went to school on Friday (I'm a teacher), which I've done many times, but when I plugged the external hard drive back into the laptop this morning my laptop would not recognize the hard drive. I think that the external hard drive is getting power - it's making a whirring noise, like it does when it's working normally - but the light on the front of the external hard drive will not light up, and my laptop does not recognize it. I've tried the external hard drive with another computer and it also did not recognize it, which makes me think it's a problem with the external hard drive and not the laptop. My fear is that the hard drive is dead, since no computer will recognize it even though it seems to be getting power. Is there any way that I can find out if this is indeed the problem? If this is indeed the problem, is there a way that I can still recover the files from the hard drive?

Any ideas? Thank you so much for any help!

Changed wall socket...

Well, I got lucky - I tried one more time when I got home. I plugged the external hard drive into my normal old surge protector and voila - my PowerBook recognized it again. I think that perhaps the other wall socket I was using didn't provide enough power...maybe?

Thank you for the advice and the commiseration, and you are exactly right - back up EVERYTHING, and often.