Hi,
have you looked in the "add to panel" tool to see if the sound applet is there?. (Right click on top panel!). 
You can also try the following commands:
sudo dpkg --configure -a
then:
sudo apt-get install -f
Also try the following command but make sure your software sources download location is set to "Main server"!:
sudo apt-get update && sudo apt-get dist-upgrade -f
See also: