Hi Robert - Right now, I'm listening to music. I went to the HP website and just played around, filling out forms with my problems and I was asked if I wanted HP to decide what I needed, so I agreed.
They said I needed SEVEN drivers, mostly Realtek wireless lan drivers and Nvidia.
It took awhile and several reboots. When it was done, the msg popped up that I had no NVidia control panel, but it said, "click here to reinstall" so I did.
I am now playing music.
I have had this problem with the Nvidia disappearing after a reboot since I got the pc. I keep reinstalling it, but this time, it was way more than that - it was the whole audio system that disappeared. I am not tech savvy at all, so getting this sound back is a major miracle. Thanks for your help.