Screen resolution drop on Ubuntu

If you find your screen resolution suddenly drops too 800×600 on Ubuntu 12.04, the following set of commands may help you resolve it. First, stop the graphical environment.

sudo service lightdm stop

Now remove all the Nvidia packages and reboot the system.

sudo apt-get purge nvidia*
sudo reboot

This will reset you to the default video driver. You now need to reinstall the Nvidia driver, which you can do by going to System settings > Additional Drivers and selecting the top option with the following name.

NVIDIA binary Xorg driver, kernal module and VPDAU library

Select this and click activate. Now reboot your system again and the Nvidia drivers will be re-installed and hopefully working again.

Gnome fails to start after switching Nvidia drivers on Ubuntu

If you’ve tried to switch to a different Nvidia graphics driver on Ubuntu and suddenly found that X / Gnome will no longer load and all you have is a command line, you can fix it by switching back to the original driver.

jockey-text -l
jockey-text -e xorg:nvidia_current

These commands will show you a list of drivers available, and then activate the standard Nvidia driver.