I updated to Ubuntu 10.04 this week, and now I’m listening to Nightwish, I suddenly felt the need to get the volume up. My mouse started on it’s way to the place the volume control-applet used to be, but it seemed to have disappeared. Luckily, this problem too is easy to fix: start the program “gnome-volume-control-applet” by pressing alt + f2. If that works, you might want to go to “System” > “Preferences” > “Startup applications”, and see if volume control is there and checked. If it’s not there, you can add it, and if it’s there and it’s not checked… well, then check it.
Problem easily fixed. Nightwish: you just started to sound a lot louder.