Built-in audio is gone

After discovering I didn't need Boom any more I uninstalled it. Upon the next restart it seems that it actually removed the Built-in audio device and now the only option left is 'Boom' - which doesn't work and outputs nothing now that the control panel is gone.

I am thoroughly ticked off because I need the bloody sound to work for a presentation in about an hour. Anyone have any clues?

 

Unfortunately I don't have an install disk. That's pretty poor coding for it to completely remove the Built-in audio device. It looks like it's happened to several other people - did they not test it?!