I simply don't have any sound on my Ubuntu 12.04 (Precise), after upgrade from 11.10.
Using this command:
sudo killall pulseaudio; rm -r ~/.pulse*, the audio comes back but when I turn it off and on again the audio is gone. Again.
Alsamixer works fine all the bars on top. And the sound configuration reveals something; it says "Salida para torpes" as well known as "Salida boba". A translation would be "Dummy output".
So I already don't know what's going on. :/