One time my sound card was no longer detected and the only way to get it working again was to reinstall Linux. I want to avoid having to do this by backing up important files for sound so that if the sound card disappears again I can fix it. Which directories should be backed up?
The easiest way is probably to install the Simple Backup Suite. It will backup all important configuration files from system directories and your home directory.
Get from the Synaptic Package Manger - sbackup