I doubt the model, OS, or even laptop or desktop make any difference for what I discovered...
here is the fix/test... If your HP computer has BeatsAudio installed on it do this,
open it, and if you can't see it on your desktop click on the "hidden" icons arrow bottom right of your screen,
right click the red circle,
left click "open beats audio"
beats opens after a few seconds,
click "Listening Experience",
click "setup"
click "stereo"
Click "quadrophonics" (or howeever the surround is listed),
Click "stereo"
Click "quad", again
click "stereo" again
close the BeatsAudio window
sound should be fine now.
occasionally I would have to test speakers, click on the stereo and quad a few times but every time this method works,,,go figure.
I found that when I move to different programs like Media-Player, Internet (firefox), youtube, and back, my audio stopped. I had been waiting for HP to do something about that for over a year...much more actually. Why does this fix it? Why does it matter? When will you send us a patch to repair this problem? There are a thousand people trying to find a remedy for this "No Audio"issue. Peasse look at the "BeatsAudio" program and fix it. Thanx. Hope this helps ya'll...at least you don't have to keep rebooting your machine to make your audio work again.