I found my x window is dead, all the graphic application have no reaction on the mouse click,so i have to change to the tty1 to work,use the Ctrl+Alt+F1 but the previous work is still need to rework.
The command ps doesn't display the xorg's thread, so I couldn't kill it.
And when I need to go back to graphic window, I must reboot the system.
sudo servicenotsudo services. :-) – Paul A Jungwirth May 19 '15 at 21:15systemctl restart display-managerbut alas it didn't help get my screen back. – Mark Jeronimus Sep 22 '20 at 14:32