The reason: NVIDIA driver caused nvidia driver before installing the wrong way.
Solution: Uninstall the latest version of the current Nvidia, installation and system matching.
At that time: The system can boot into ubuntu, but the card is lost in the command line interface, graphical interface.
Solving steps:
1) in FIG user name and password to enter the system
2) uninstall the old driver (nvidia):
sudo apt-get remove nvidia-* sudo apt-get autoremove
3) The .run file something clean uninstall:
sudo nvidia-uninstall
4) reboot the system, use the command to see if a clean uninstall:
lsmod | grep again
5) Close X-Window:
sudo service lightdm stop
6) Install the latest Nvidia
sudo ./NVIDIA-Linux-x86_64-381.22.run -no-x-check -no-nouveau-check -no-opengl-files
7) Restart X-Window:
sudo service lightdm start