I've had an 200GB Seagate external hard drive (ST3200823ARK ) for over five years. Its worked great.
Three weeks ago it failed to turn on completely. The power light went on but the disk drive light failed to turn on. I thought I was in dire trouble since the drive had lots of music on it; in addition to other documents.
I'd never abused the external hard drive and it had always stayed on my desk. Unfortunately, it had been over five years since I purchased it, and it had fallen out of warranty. Taking it to a repair facility or using a data recovery service would have been very expensive. Seagate would have charged between $1700 to $3500 and a more local shop would have charged from $500 to $1700.
I finally decided to disassemble the drive enclosure using an online doc from instructables.com. Here's the link: http://www.instructables.com/id/Disassemble-Seagate-External-Harddrive/
Luckily for me the drive was never damaged, but it seems the electronic enclosure used to power it up and interface the Barracuda IDE drive to USB and firewire failed!
Once I removed the drive from it's enclosure I was able to use the drive as an internal hard drive and I was able to get to all my files.
So, if your drive is out of warranty and you feel the drive was fine up until the failure it could be that all you need to do is disassemble the external hard drive enclosure and see if the internal hard drive still works.