since you have lost sound everywhere, perhaps you can consider following mads' tutorial to remove pulse audio and replace with alsa.
I do not know if there is a procedure on Mint12.
I seldom have trouble with pulse audio for many distros on many computers, usually sound works out of the box.
However on a few occasions I have no sound at all, and removing pulse audio did the trick
One of those occasions was LMDE-gnome, this was weird, since all along it worked, on reinstallation it did not work.
Another one, just happened today, on new LMDE-201204-xfce-RC iso, sound works on one computer, but no sound everywhere on an old computer ( most other distros have no trouble). upon uninstalling pulse audio and replace with alsa, sound works everywhere.