Ubuntu16.04 change Normal user rights <1000:1000 to 0:0> only after the guest identity into the system

When a normal user enters the system, sometimes they need to switch the root user, and then change the normal user rights to root user rights. Then, when you are ready to enter the system again, the discovery can only be entered as guest.

So find a variety of ways to change back, the following is the solution I encountered the situation:

1. Restart Ubuntu, press and hold shift to enter the Grup menu, or wait for the Grup menu to appear.

2. Select the Recovery Mode menu and press E to edit.

3, the RO recovery nomodeset to RW single init=/bin/bash, and then F10 into the root one-user mode.

4, vim/etc/passwd into the editor, the user rights from 0:0 to 1000:1000, and finally save the exit (: WQ), restart the computer.