Happy New Year TwentyTen!
How many times have you “forgotten” a root password? Or been given control of a server set up by someone else? Hey it happens.
CentOS Password Reset
At the GRUB Loader, select the installation to reset, press A to append and press ENTER.
You will be presented with a prompt that looks similar to this: grub append> ro root=LABEL=/
Press the SPACEBAR once and type the word single and press ENTER. This will boot to single-user-mode.
You will then get the shell prompt (hostname)#
Change the root password using the normal command: passwd root
Reboot and login. That’s all there is to it!