Sound settings are missing

Install gnome control center and pulseaudio again to fix this issue:

sudo apt-get install gnome-control-center

If still doesn't fix your problem:

sudo apt-get install ubuntu-desktop

If after installing gnome-control-center you still have noise problem try to install pulseaudio:

sudo apt-get install pulseaudio

For those who only need to restore sound settings, the alternative is to install unity-control-center (you need to ensure gnome-control-center is installed before doing this), e.g.

sudo apt-get install unity-control-center

that works in Ubuntu 14.04, 16.04 LTS , should also work in latest version