How to change the graphics card driver via terminal?
For 14.04 and upwards, jockey-text isn't installed or available in the repository. I have just recovered from an issue where the Noveau driver caused my computer to lockup completely after logging in and I needed to go back to the nvidia driver. Here's how I did it:
At the login screen, instead of logging in I went to a terminal using CRL + ALT + F2 Type
ubuntu-drivers devices
to get a list of your devices and identify the one you want. My output looked like this:
$ ubuntu-drivers devices
== /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0 ==
modalias : pci:v000010DEd00000391sv00001462sd00000630bc03sc00i00
vendor : NVIDIA Corporation
model : G73 [GeForce 7600 GT]
driver : nvidia-304 - distro non-free recommended
driver : nvidia-173 - distro non-free
driver : xserver-xorg-video-nouveau - distro free builtin
driver : nvidia-304-updates - distro non-free
I wanted nvidia-304 so I typed:
apt-get install nvidia-304
Then I rebooted and confirmed using the desktop appliaction Additional Drivers that I was indeed using the driver I had chosen.
To unistall the proprietary drivers, you should be able to simply do:
sudo apt-get remove fglrx fglrx-amdcccle fglrx-pxpress
if you have intalled the standard drivers, or
sudo apt-get remove fglrx-updates fglrx-amdcccle-updates
if you have the "updates" one.
Remember to manually delete the file /etc/X11/xorg.conf; otherwise X will still search for the proprietary drivers and will not start correctly (most of the times).
This would normally re-enable the default (open-source) drivers.
I just wanted to chime in here because I just had the exact same problem (running Ubuntu 14.04 LTS). I selected a different video card driver in the system settings, and after rebooting, my computer prompted me to start in low-graphics mode.
What fixed the problem for me was deleting /etc/X11/xorg.conf. Now, X11 is the window manager used by Ubuntu, and it loads all files ending in .conf for its settings (at least - that's what 3 minutes of Google told me).
Since I would be hesitant to outright remove files that may in retrospect prove essential, I renamed it to something else:
sudo mv /etc/X11/xorg.conf /etc/X11/xorg.conf.backup
sudo reboot
This fixed the problem for me.
Initially, my idea was to use the command line to change the video card driver back. I resorted to trying this idea because I couldn't find a way to change the video card driver. One suggested answer said to use jockey-text (How to change proprietary video driver using the command line?); however, starting with 14.04 jockey-text isn't part of Ubuntu anymore.
Some additional research: I read that X11 doesn't create an xorg.conf by default anymore. Above solution might not work for you.