Instale ou reinstale os drivers da placa de som e os pacotes necessários:
sudo apt-get install build-essential linux-headers-'uname -r' alsa-base alsa-firmware-loaders alsa-oss alsa-source alsa-tools alsa-tools-gui alsa-utils alsamixergui
Ou:
sudo apt-get --reinstall install build-essential linux-headers-'uname -r' alsa-base alsa-firmware-loaders alsa-oss alsa-source alsa-tools alsa-tools-gui alsa-utils alsamixergui