I did something stupid. I had an issue with my xubuntu not recognizing an external LG monitor. It used to work, but after one uncheck of "Use this monitor" it was turned off and later when I wanted to turn it on, it stopped working. But currently, I have a bigger issue.
In my tries to solve this, I found "Ubuntu 16.04LTS extended display not working". And without thinking I ran: 1.Run sudo apt-get purge nvidia-* 2.Run sudo add-apt-repository ppa:graphics-drivers/ppa 3.Run sudo apt-get update 4.Run sudo apt-get install nvidia-387
My laptop is Lenovo B50. After restarting ("startx" command) the xserver does not start:
"Data incomplete in file /etc/X11/xorg.conf Undefined Screen "nvidia" referenced by ServerLayout "layout". ... Fatal server error: no screens found(EE) "