I dunno if this topic is still alive, but i need help.
I did all that you said, but all that happened was this:
I need to know what just happened and how can i fix it, if it's possible, please. Thank you.
Try running
sudo apt install libgconf-2-4
in your terminal. After putting in your password and confirming by typing Y
(May vary in your system language) it should install the missing library. At least that’s what did it for me.
Also judging by the borders of your window, your Ubuntu installation is outdated. you should upgrade to the latest version (20.04 as of now) when you can.