No GUI shell in Ubuntu 16.04 after update - NVIDIA graphics card

Question

Over night, so possibly after an update, my GUI login into Ubuntu 16.04 does not work anymore.

So I open another console (Ctrl+Alt+F3) and everything works fine.

I tried the stuff I found elsewhere: something with removing ~/.Xauthority.

In ~/.xsession-errors file I found at least the keyword, that others used to detect their errors: something with GLX.

In the end I did:

sudo apt autoremove nvidia-*
sudo apt install nvidia-current

GUI login still does not work.

.xsession-errors says:

extension "GLX" missing on display ":0".
openConnection: connect: No such file or directory
cannot connect to brltty at :0
upstart: ..... ...

Answer 1

for all the dummies like me: first

sudo apt purge nvidia*

find out which graphics card you have with:

lspci | grep VGA

then look up which driver you need on nvidia.com search for it in the repositories with

 sudo apt-cache search nvidia-* 

(or add further numbers to shorten the list). Install it with

sudo apt install nvidia-YOURNUMBER

then

reboot