How can I uninstall a nvidia driver completely ?
For Ubuntu 12.04
Commands can be executed to terminal. You can open a terminal with Ctrl + Alt+T keys combo.
If you remove --purge the nvidia driver you will be OK. No need to blacklist something, but sometimes maybe a force-load of the nouveau module needed.
First uninstall completely the driver.
Search what packages from nvidia you have installed.
dpkg -l | grep -i nvidia
except the package nvidia-common all other packages should be purged.
If you want to be sure that you will purge everything related to nvidia you can give this command
sudo apt-get remove --purge '^nvidia-.*'
the .* in the end means (Purge everything that begins (^) with the name nvidia-)
BUT
above command will also remove the nvidia-common package and the nvidia-common package has as a dependency the ubuntu-desktop package.
So after above command you should also give the installation command for ubuntu-desktop package
sudo apt-get install ubuntu-desktop
Also sometimes the nouveau driver get blacklisted from nvidia driver. With purge command it should UN-blacklisted. If you want to be sure that nouveau will be load in boot, you can force-load it by add it to /etc/modules
echo 'nouveau' | sudo tee -a /etc/modules
Last , search for the xorg.conf file and remove it as well
sudo rm /etc/X11/xorg.conf
In summary
sudo apt-get remove --purge '^nvidia-.*'
sudo apt-get install ubuntu-desktop
sudo rm /etc/X11/xorg.conf
echo 'nouveau' | sudo tee -a /etc/modules
Although all above commands not needed, this is my way to completely purge the nvidia driver and use the open source nounveau.
I just used the nvidia-uninstall.
sudo nvidia-uninstall
In my case I got the driver directly from the nvidia website.
I realize that this is an old answer, but I have to add an answer here for sake of clarity and system stability.
First off, the * is an expansion operator for the shell which will grab everything and remove a lot of files you don't need to remove. The safest way to remove the nvidia driver is to do
$ dpkg -l | grep nvidia
Search for nvidia-xxx.xx version or nvidia-driver-xxx.xx version and then type
$ sudo apt purge nvidia-xxx.xx
It will only remove that package but will also flag its dependencies for removal.
To remove the dependencies is easy.
$ sudo apt autoremove
$ sudo apt autoclean
So for example, if you have the 390.xx package installed, it would be.
$ dpkg -l | grep -i nvidia
ii libnvidia-cfg1-390:amd64 390.48-0ubuntu3 amd64 NVIDIA binary OpenGL/GLX configuration library
ii libnvidia-common-390 390.48-0ubuntu3 all Shared files used by the NVIDIA libraries
ii libnvidia-compute-390:amd64 390.48-0ubuntu3 amd64 NVIDIA libcompute package
ii libnvidia-compute-390:i386 390.48-0ubuntu3 i386 NVIDIA libcompute package
ii libnvidia-decode-390:amd64 390.48-0ubuntu3 amd64 NVIDIA Video Decoding runtime libraries
ii libnvidia-decode-390:i386 390.48-0ubuntu3 i386 NVIDIA Video Decoding runtime libraries
ii libnvidia-encode-390:amd64 390.48-0ubuntu3 amd64 NVENC Video Encoding runtime library
ii libnvidia-encode-390:i386 390.48-0ubuntu3 i386 NVENC Video Encoding runtime library
ii libnvidia-fbc1-390:amd64 390.48-0ubuntu3 amd64 NVIDIA OpenGL-based Framebuffer Capture runtime library
ii libnvidia-fbc1-390:i386 390.48-0ubuntu3 i386 NVIDIA OpenGL-based Framebuffer Capture runtime library
ii libnvidia-gl-390:amd64 390.48-0ubuntu3 amd64 NVIDIA OpenGL/GLX/EGL/GLES GLVND libraries and Vulkan ICD
ii libnvidia-gl-390:i386 390.48-0ubuntu3 i386 NVIDIA OpenGL/GLX/EGL/GLES GLVND libraries and Vulkan ICD
ii libnvidia-ifr1-390:amd64 390.48-0ubuntu3 amd64 NVIDIA OpenGL-based Inband Frame Readback runtime library
ii libnvidia-ifr1-390:i386 390.48-0ubuntu3 i386 NVIDIA OpenGL-based Inband Frame Readback runtime library
ii nvidia-compute-utils-390 390.48-0ubuntu3 amd64 NVIDIA compute utilities
ii nvidia-dkms-390 390.48-0ubuntu3 amd64 NVIDIA DKMS package
ii nvidia-driver-390 390.48-0ubuntu3 amd64 NVIDIA driver metapackage
ii nvidia-kernel-common-390 390.48-0ubuntu3 amd64 Shared files used with the kernel module
ii nvidia-kernel-source-390 390.48-0ubuntu3 amd64 NVIDIA kernel source package
ii nvidia-prime 0.8.8 all Tools to enable NVIDIA's Prime
ii nvidia-settings 390.42-0ubuntu1 amd64 Tool for configuring the NVIDIA graphics driver
ii nvidia-utils-390 390.48-0ubuntu3 amd64 NVIDIA driver support binaries
ii xserver-xorg-video-nvidia-390 390.48-0ubuntu3 amd64 NVIDIA binary Xorg driver
To verify, you can do
$ apt-cache search nvidia | grep driver
nvidia-settings - Tool for configuring the NVIDIA graphics driver
ubuntu-drivers-common - Detect and install additional Ubuntu driver packages
vdpau-driver-all - Video Decode and Presentation API for Unix (driver metapackage)
xserver-xorg-video-nouveau - X.Org X server -- Nouveau display driver
nvidia-340-dev - NVIDIA binary Xorg driver development files
nvidia-384 - Transitional package for nvidia-driver-390
nvidia-384-dev - Transitional package for nvidia-driver-390
nvidia-driver-390 - NVIDIA driver metapackage
nvidia-utils-390 - NVIDIA driver support binaries
xserver-xorg-video-nvidia-390 - NVIDIA binary Xorg driver
bumblebee-nvidia - NVIDIA Optimus support using the proprietary NVIDIA driver
kubuntu-driver-manager - Driver Manager for Kubuntu
kubuntu-driver-manager-dbg - Driver Manager for Kubuntu -- debug symbols
nvidia-common - transitional package for ubuntu-drivers-common
nvidia-304 - NVIDIA legacy binary driver - version 304.137
nvidia-304-dev - NVIDIA binary Xorg driver development files
nvidia-340 - NVIDIA binary driver - version 340.107
nvidia-387-dev - Transitional package for nvidia-driver-390
nvidia-387 - Transitional package for nvidia-driver-390
nvidia-390-dev - Transitional package for nvidia-driver-390
nvidia-390 - Transitional package for nvidia-driver-390
nvidia-driver-396 - NVIDIA driver metapackage
nvidia-utils-396 - NVIDIA driver support binaries
xserver-xorg-video-nvidia-396 - NVIDIA binary Xorg driver
Once you've targeted the package to remove, do
$ sudo apt purge nvidia-390 -y
$ sudo apt autoremove -y
$ sudo apt autoclean
Make sure to install whatever driver you plan on using right after you do this and if you don't have livepatch because of whatever reason, just reboot your system and you should be good to go.
This way you don't ever have to worry about removing system dependencies while clearing out your drivers. You'll have a sane and stable system afterwards and don't have to worry about re-installing other packages that your system may depend on. That's apts job, not yours.