If the user does not have sudo permissions, then method one is not available and needs to go into grub to modify the kernel mirroring boot parameters. The Ubuntu version used in this article is 14.04.4, the process is as follows:
1. Restart the computer long press the SHIFT key until enter into the Grub boot mode, select the second line of Ubuntu advanced options, select Direct Enter, such as:
2, enter the following screen, see there are some options, then do not press ENTER, press e into (recovery mode) compile kernel to start parameters
3, the key time to, the fourth line, you will see a line linux/boot/vmlnuz-4.2.0-27-generic ... ro recovery nomodeset,
Delete Recovery nomodeset
3. Then add the quiet splash RW Init=/bin/bash After you have just removed it. Then press F10 to start.
4 If all the fight, after the system directly into the root mode, enter: passwd, the system will prompt you to enter a new password, the end.
Ubuntu forgot Password