One of the worst feelings in the world is a computer that won't boot up. How can you fix a problem if you can't even access the hard drive? A good preventative measure is to create a rescue disk for your computer. Watch our video then head back here for the steps.

Your computer may boot up into a safe or recovery mode all on its own--which is great--but if the power's fine and the dang thing just won't boot, you need a rescue disk. If you still have Windows or Mac OS X, your install disk acts as a recovery disc. Or you may have a special recovery disk from the manufacturer.

Put your system or recovery disk in the CD-drive and then boot from CD (we have a separate Quick Tip that shows you how to do that). It should take you to some sort of recovery screen that gives you limited access to the computer.

Depending on the problem, that may be all you need. However, what if you've lost your install disk? Or, as is sometimes the case with Windows rescue disks, what if the recovery program you have won't let you copy files or edit text. We have some help for you. Bootable Linux CDs, like Knoppix here, to the rescue!

I should note that Knoppix has trouble reading the Windows file system called NTFS. It's fine with the FAT32 system. For NTFS users, try Bart's Preinstalled Environment. First, download the ISO file of the bootable Linux of your choice. I'm going with Knoppix from Knoppix.net.

Next, burn the ISO image to a blank disc. We have a Quick Tip on how to do that, too. Then boot from the Linux CD. Now you should have access to your hard drives and all the data on them.

Let's say you want to recover data off the hard drive.

First, right click on the drive and choose mount.

Right click on the drive, choose actions and change read/write. Say, "Yes, you want to make the disk writable."

Now you can plug in an external drive, like a thumbdrive. Make it writable as well, just the way you did for the hard drive. Then drag files across to save them.

Or, let's say you've tracked down the problem to a corrupted file.

Go to the big K, choose editors, and open a text editor like KWrite. Choose file: open select device, find your hard drive, probably called hda1 and browse to the file you wish to edit. Having set the read/write parameters earlier, you can now edit the file and save it back.

When you're done, shut down the computer and pull out the CD. Now you can try rebooting from the hard drive to see if your fix worked.

That's the most basic way to do this. Once you get the hang of Knoppix, you can make a more customized CD or even a rescue thumbdrive.