I'm totally newbie to Ubuntu after years of MS Windows. Please excuse my mitakes. The icon was located in Gnome Panel 2.30.2. and it adjust the level of sound.
31 Answer
Just right click on the panel, and select Add to Panel. Scroll down, and look for Indicator applet. Click the Add button. That should add the indicator. If that does not solve your problems, open a terminal, by pressing Ctrl + Alt + t
Type
rm /home/wissen16/.gconf/apps/panel/
And log out for the settings to take effect.
