No Audio Output Device is installed

I have no sound on my laptop. Sometimes it will be there and sometimes it won't. Right now it is saying "No audio output device installed". I go to device manager and the only thing listed under Sound, video and game controllers is: "Bluetooth Hands-free Audio and Bluetooth Stereo Audio".

I have an HP Pavilion Laptop running Windows Vista.

Thanks for the help!

via Bleeping Computer Last 20 Posts http://www.bleepingcomputer.com/forums/t/317603/no-audio-output-device-is-installed/