Ok, try this.
This is pretty advanced so take it very easy. If you do it wrong it could ruin your system and that is not my fault (I tried it on my system just to make sure). Be careful, m'kay?
If you have the installation media on CD, boot of that. (RH CD1)
when you see the boot: (where you usually press ENTER to install), type "linux rescue" + ENTER
Let the installation program start, use language "English" + [OK], set your Keyboard type + [OK]. You will get a question about the installation wanting to find your RH installation, agree to that.
After a couple of seconds you get a success-message and you can press [OK] to return to shell.
if this file is empty (was not found) try
You should get a file with all your users in it. Find your root user (usually on the top).
it looks like:
or something similar.
use your arrow-keys to get to the first character after root: (in the example above, the "!".
press the "x" on your keyboard. This will remove one character every press. Remove everything to the next : so the line looks like
save the file with the following key sequence
[ESC] : wq!
in the shell-prompt, type "exit" and the system will reboot.
Remove the CDROM and boot your system up.
at the loginprompt type root + ENTER.
Change root-password with the command
and don't dare to forget it again