well in case u forget ur new password
u can go to boot loader screen and again start ur computer
in run level 1 in single user mode,then it will bring u to shell prompt
frm there u can again run the "passwd" command and change or retype ur old password
but in case u have a boot loader with password u cannot break ur linux root password. as if u forget ur boot loader password it will not allow u to edit at ur linux screen and u cannot do the rest of the job.fr that u have to use "rescue".