reinicie a concha do gnomo
killall -3 gnome-shell
Dark Dotterel
killall -3 gnome-shell
If the gnome reponses, minimally:
Alt + F2, than typing 'r' and ENTER
If it not, go to a lower terminal (CTRL+ALT+F1,2,3,4 or whatever till 7)
Login, and kill gnome-shell (it will restart)
$ killall -HUP gnome-shell