Comment 3 for bug 324879

If you click on the speaker in the panel, a window should open with many volume controls. If it doesn't, launch "gnome-volume-control" from a terminal.
Master, PCM, *and* Wave have to be *all* on, otherwise you won't be able to hear sound (try settings of around 70%, and make sure all 3 channels are unmuted of course. I get distortions if I set PCM to 100%, so always use less than that).
If you do not see at least three (double-)sliders labelled Master, PCM, and Wave, please tell me which ones you see.

And if you don't get responses after a few days from bugs you posted, you can always try to post a question ( https://answers.launchpad.net/ubuntu ), or open a thread in the community forum ( http://ubuntuforums.org/ ) instead.