Recently I have seen a lot of posts on the Internet about Laptop Sound suddenly not working on Ubuntu 12.04 systems after the Updates have been done. I experienced this when trying to load an old HP P4 laptop. (Model ze5715) Below is a summary of what happened, and how I was able to finally to get this Laptop loaded using Mint 13 Xfce:
Going on a guess, I reloaded this laptop with Mint 13 Xfce, and then immediately did a complete uninstall of PulseAudio. Since use of the ALSA sound system is already well integrated into Mint 13, there was no need to install anything to still have a volume control to use once PulseAudio was uninstalled.
sudo add-apt-repository ppa:otto-kesselgulasch/gimp
sudo add-apt-repository ppa:libreoffice/libreoffice-4-2
sudo apt-get update
add the following command to completely remove PulseAudio
sudo apt-get autoremove pulseaudio
Note: Once PulseAudio is uninstalled, the “Mixer” Item must be added to the bottom Panel to again have a volume control on the desktop.
So based on the above solution to get this laptop loaded, it would appear that some update related to PulseAudio is causing this “sound not working” situation on Laptops that are using the Ubuntu 12.04 repositories. (Ubuntu 12.04 LTS, or any other version of Linux that is based on Ubuntu 12.04)