Settings not opening in Ubuntu 20.04
I found a solution to this:
Go into terminal and type:
xrandr --auto
If that didn't work try typing:
xrandr --current
You will get a list containing vga, vga1... with most of them displaying disconnected.
Ignore LVDS-1 connected and search for the other one that has connected; most likely it will be VGA-1.
If so then type the following command:
xrandr --auto && xrandr --output VGA-1 --off
Please note that I have given VGA-1 as it was in my case, but you may have to change it to whatever you find connected other than lvds-1.