cannot install nvidia-390 driver, ubuntu 18.04

Question

I accidentally uninstalled my active kernel as well as my graphics drivers using this command from a StackExchange suggestion:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' | xargs sudo apt-get -y purge

After reinstalling the kernel, I am working on the graphics drivers.

ubuntu-drivers devices returns:

== /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0 ==
modalias : pci:v000010DEd00001C03sv0000196Esd0000119Fbc03sc00i00
vendor   : NVIDIA Corporation
model    : GP106 [GeForce GTX 1060 6GB]
manual_install: True
driver   : nvidia-driver-390 - distro non-free recommended
driver   : xserver-xorg-video-nouveau - distro free builtin

sudo ubuntu-drivers autoinstall returns

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have requested an 
impossible situation or if you are using the unstable distribution that some 
required packages have not yet been created or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 nvidia-driver-390 : Depends: nvidia-dkms-390 (= 390.48-0ubuntu3)
                 Recommends: libnvidia-compute-390:i386 (= 390.48-0ubuntu3)
                 Recommends: libnvidia-decode-390:i386 (= 390.48-0ubuntu3)
                 Recommends: libnvidia-encode-390:i386 (= 390.48-0ubuntu3)
                 Recommends: libnvidia-ifr1-390:i386 (= 390.48-0ubuntu3)
                 Recommends: libnvidia-fbc1-390:i386 (= 390.48-0ubuntu3)
                 Recommends: libnvidia-gl-390:i386 (= 390.48-0ubuntu3)
E: Unable to correct problems, you have held broken packages.

sudo apt install nvidia-390 returns

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package nvidia-390 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or is 
only available from another source
However the following packages replace it:
  libnvidia-gl-390 nvidia-kernel-source-390:i386 nvidia-headless-no-dkms-390:i386 libnvidia-gl-390:i386
  nvidia-kernel-source-390 nvidia-headless-no-dkms-390

E: Package 'nvidia-390' has no installation candidate

sudo apt install -f returns:

Reading package lists... Done 
Building dependency tree 
Reading state information... Done 
The following packages were automatically installed and are no longer required: 
amd64-microcode intel-microcode iucode-tool libc-dev-bin thermald
Use 'sudo apt autoremove' to remove them.

sudo add-apt-repository ppa:graphics-drivers returns the warning: This PPA is currently in testing, you should be experienced with packaging before you dive in here.

I am not experienced with packaging and do not want to mess something else up again, so I did not run it.

A side question: does anyone know how I can be certain that my kernel is running properly? I.e. that if I restart my computer it will boot?

uname -r returns:

4.15.0-43-generic

So I believe it is functioning. Is there anything else it would be smart to check?

Answer 1

nvidia-390 is part of the graphics-drivers PPA.

Run sudo /usr/bin/nvidia-uninstall to uninstall a manually installed driver, if you still got one.

Remove everything of your old NVIDIA driver (simulate first):

sudo apt remove --purge -s nvidia-*
sudo apt remove --purge -s libnvidia-*

If only nvidia packages are there to be removed, remove really:

sudo apt remove --purge nvidia-*
sudo apt remove --purge libnvidia-*

Run sudo apt update and ubuntu-drivers devices again.

If nvidia-390 is still recommended, add your output of sudo ubuntu-drivers autoinstall again.