ZhoubaWiki:ResetRootPassword

Recovering Root Password On Debian And Grub2

On the grub boot screen type e for edit. Next edit the line starting with linux, at the end add init=/bin/bash. It should look like this.

linux /boot/vmlinuz-version root=UUID=hex ro quite init=/bin/bash

Next hit Ctrl-X to boot, you should land on a prompt without having to type your password. Next enter the following two commands:

mount -o remount,rw /
passwd

Enter the new password twice, type the following:

sync
reboot

You should be all set!