From time to time, the display won't work correctly after my system upgrade or software upgrade. The following is the SOP to solve this problem:
a.
1. don't use Nvidia's graphic card
b.
1. ctrl + alt + F1 to change to another tty
2. sudo service lightdm stop to stop X
3. sudo ./XXXX-nvidia.xxx.run
4. sudo service lightdm start to activate X
