I go to system settings and appearance is gone. I tried searching it in the dash and it is not there. When I right click the desktop and select "Change background" the system settings window opens. I tried going to the ubuntu software center and installing it from there it installed and popped up on my launcher. I tried clicking it and it opened up the system settings menu and appearance was still not there. I unlocked it from my launcher and searched for it in the dash and it was not there. Please help.