I have been very lucky perhaps, since I have only experienced 4 hard disk break downs after using computers for around 20 years.
The first one occured only 2 days after I took a complete backup of it, so I did not loose any important stuff, and it was no need to try to rescue any files from it.

The second one was on a laptop used only for surfing the net, no important stuff on that one that was worth rescuing either. But now I started to be interested in what I could have been able to rescue myself, without sending the disk to a "diskdoctor" or buying expensive software.
After searching the net I found a few free rescue CDs, one of them was a Linux distribution called Knoppix.
I downloaded the software and burned a bootable CD, and tried this in the crashed laptop.
The laptop started without any problems, and to my delightful surprise the hard drive and all its content was available, and I could copy any files I wanted to e.g. another disk or network location.

Recently another computer of mine crashed, and that did initially not cause any big concerns since I had backups on an external USB hard drive.
But when I tried to access this external USB hard drive I was very disappointed, since this did not work, at least it would not be detected and accessible from both Windows XP and Windows Vista.
Again I tried my Knoppix CD, and again both the crashed internal hard disk and the external USB hard disk was available and accessible.

Why can Linux read and access hard drives that Windows can't even find?

I had no time to wonder about this, since I needed to copy all my important files from the two crashed hard disks over to another external USB hard disk.
Again Linux had come to my rescue, and almost all files (except the corrupt/damaged ones) on the troublesome hard drives was rescued.

If you ever need a free disk rescue tool, then try Knoppix, Ubuntu or any other free Linux distribution you prefer.

Good luck with your hard disk rescue!