Reboot. At the LILO prompt type the name of your kernel to load, followed by "init=/bin/sh" on the same line, w/o quotes.
This get's you in at runlevel 1, type "passwd" and enter a new root passwd.
*If you got GRUB, search LQ for the appropriate GRUB line.
**YES, it is a std feature of Linux if you didn't passwd the bootloader, so no posting "I found a security leak". :-]