If you want the volume control like in previous version (9.10 and earlier) of Ubuntu you'll need to edit a file.
Open the terminal and type:
gksu gedit /etc/xdg/autostart/gnome-volume-control-applet.desktop
In the file that opens, look for this line:
That line prevents the older volume control from showing on the panel. Change it by putting a # in front of it so it looks like:
Save the file then log out and back in and the volume control should be back.
If you find that you have 2 volume controls and you want to keep the older control, remove the app called "indicator-sound" via synaptic.