Reset Linux root Password

All we need is a LiveCD Linux system

In some linux systems the username/password database is located at "/etc/passwd"
If you have any other linux system just search on google where the username/password file is located.

I am here telling Backtrack 5
Password is located at "/etc/shadow" but its encrypted. To make the change we need to mount first the partition where our linux system is located. go to that location /etc/shadow
edit it via nano editor

nano /etc/shadow then you will see something like this root:xxxxxxxxx:15098:0:99999:7:::

here above instead of xxxxxxxxxxx you will see other symbols when you will open that file in your pc. Just remove all the xxxxxxxxxxxx(symbols) next to root
example :-
Before : -  root:xxxxxxxxx:15098:0:99999:7:::
After :-    root::15098:0:99999:7:::
Save the file and reboot the system and you will find blank password of root.