pulseaudio -k, followed by
pulseaudio, run in a terminal.
If that fails, try sticking the text in the following link in a shell script called
alsacontrol.sh(Using text editor), making it executable from the permissions tab when you right-click it, and then run it when needed by opening a terminal and running
How this works:
Pulseaudio is a layer used for bringing sound from most applications to ALSA, which then works with hardware. If Pulseaudio is hanging, then pulseaudio can be restarted. If ALSA is malfunctioning, you may restart ALSA using the second script.
Reference(Script moved to Pastebin in case source is down): http://ccrma-mail.stanford.edu/pipermail/planetccrma/2007-July/013484.html