If you stick the RedHat CD into the drive, one of the boot options is a rescue disk. That should let you at least reset the root password, and from there you can just delete and recreate your normal user account.
This time though, consider picking a password you can at least remember long enough to get into your system upon restarting.
I am talking about a Red Hat linux O/S. I installed it and created a user name and password but did'nt write it down.
I had to boot my P.C. and I can't do anything with it because I forgot the user name and password.