I got no sound on 12.04 - it's an amd64 desktop with SB Audigy card that has worked in all previous incarnations of Ubuntu
I have tried alsa mixer and sound settings. All volume is up and all mutes are off.
I tried installing alsa drive modules and got this:
E: Unable to locate package linux-alsa-driver-modules-3.2.0-25-generic E: Couldn't find any package by regex 'linux-alsa-driver-modules-3.2.0-25-generic'