Linux graphical interface disappeared

sounds like you messed up your xorg.conf file so maybe try recofiguring X and try again.
sudo dpkg-reconfigure xserver-xorg

You on your way to being a Linux master, you have the right attitude.

Thanks for the kind words, I am always happy to learn something new, and looks like lunixcnc and linux in general a lot to learn.

I use the terminal.

I have no problem with terminal, I have problems how exactly it all works. BTW, command line was reminded pleasant nostalgic memories about my first computer zx spectrum. I was fooling around with this computer as a child, even tried to program something on it.

I'm tried to add this execute permission bit, but still had same issue.

No need to use sudo as it doesn’t modify any files.

Also it would appear it requires xinput to run.

If you look at the last line of the error, the error report is it can't find "/usr/bin/xinput"

Thank you very much for this tip, finally it worked. This program much better than "xinput_calibrator". I had issue with mirroring X axis and with "xinput_calibrator" I had to manually fill in the "Coordinate Transformation Matrix" in my case, but this program did everything by itself perfectly! Thanks a lot again!

No worrie, my screen was originally mirrored in the Left - Right & Up - Down and it was just all out of whack, xcalibrator was so much more easier to get a great solution.

OK Andy, is there anything you can't do ?

You haven't got a BSB Championship up your sleeve as well ?