This is one of the problem faced by many person’s“what if i lost the root password”First thing that comes in mind is “use single user mode” but the answer is NO.
So the BIG QUESTION IS HOW TO proceed further
follow these steps
1) on grub-boot prompt. press “e” to enter edit mode
2) then press downarrow to reach the line that starts with “kernel “ press “e” again
3) at the end of this line type in “init=/bin/sh” or “/bin/bash”
4) then press enter to make that change and press “b” to boot in a few seconds you will be on your “#” prompt
5) only one step left “mount -o remount rw /”
this step is necessary coz in this case root file system is mounted as read only.
6) finally type “passwd” and you get the screen to change the password
and then type in “init 6″ or “reboot”
NOTE FOR TECHNICAL USERS
those who are looking for the technical details, the main work is the init command that we passed as an argument to kernel, it told kernel to specifically run the command specified in parameter instead of working on normal routine.
TRICK = if you have any program you wish to run instead of this then you can do that too using init command only.