Ubuntu repair when it starts in graphical mode - Safe mode

If you ever change the system or the xorg.conf file and see that the system can no longer access the GUI, use safe mode.
Steps:
Turn on your computer, you'll see all the options in the grub.
Select from ubuntu in safe mode
Select the low failsafe mode menu, select the user and write your password.
With this access the system via the GUI and may recover their files or to repair