I have an external hard drive, in addition to a thumb drive, for back ups on my important papers. While the thumb drive is more reliable, it does not have the space required for all my stuff. Losing my project thesis I got an "A" on would truly bite. Well, I've had issues with the hard drive since the warranty ran out several years ago. It's a USB, or Universal Serial Bus connected device made by Western Digital, a company lacking good technical support.
As always, this is for informative purposes only. You break it, your bad.
You can tell when these things are messing up when an error message pops up in the taskbar on your computer. When you pull up the "My computer" in Windows xp or prior or just "Computer" in Windows Vista (trash) and Windows 7. There will be a similar message with MAC, probably some tree-hugging, dirt loving sentence like "Your component needs to be recycled, be kind to mother earth." Well whatever it is, this should help save the planet (yeah right) and more importantly, your wallet. These hard drives are not cheap. The problem is that they overheat and it's due to a defective design of the case (every one of them I've seen has this problem).
For this operation, you need a blade type screwdriver and some common sense. Handle the hard drive gently or you will wreck it. Unplug the USB or Firewire for you MAC people along with the power cord (if any). If this is a Western Digital like My Book, your job is easy. Simply pry off the cover from the frame with the screwdriver. Easy does it because you want to save the plastic frame the hard drive actually attaches to. You can discard the cover (throw it away) as long as it isn't under warranty, otherwise save it for posterity.
The hard drive itself is secured into the frame with rubber grommets. You can remove it easily, but don't throw the frame away as it protects the hard drive somewhat from shocks and will help keep it ventilated. So take the hard drive out and carefully set it aside. There is a little plastic button that's supposed to be a part of the on/off switch; break it out. Then you can put the hard drive (carefully) back in the frame it's supposed to live in. Attach the leads and as long as you didn't wait too long and cook the hard drive, you're done. Keep it standing up and keep it in a place where it won't get knocked over. It may not look as nice, but it should work if you did it right. Cost $0: Maranatha!
My apologies to Mac people, by the way. I'm a PC and I'm crazy anyway.