Ever since I used Gnome Shell Extensions, I've been feeling the need to restart the shell from the console, because its bugs sometimes.
Switch to the console using CTRL+ALT+F1 (to switch back to the DISPLAY use CTRL+ALT+F7).
Then, find out which display you're using by using the "w" command.
In the FROM column you'll see your display. Most of the time it's ":0".
Export that display from the console using the following command:
After that enter this following command :
And switch back with CTRL+ALT+F7 to retrieve your desktop with gnome