Sudden "no Audio Output Device Is Installed" Message

I noticed this afternoon that my laptop (Windows 10) wasn't generating sound. I've had similar issues once in a while previously, so I tried the usual things. Removing and plugging headphones in made no difference. I ran the Windows 10 setting sound troubleshooter which said a restart of the system was needed. When the system restarted, there was still no sound, but since then the system has shown the message "No audio output device is installed" message instead, with the audio icon x-ed out.

Based on generic online advice on this issue, I tried rolling back the sound driver, uninstalling and reinstalling the device (that causes a crash, but I'm back to where I was with the device showing up in device manager but the system still saying it's undetected after it comes back up), etc. with no improvement. I even tried downloading and installing a driver from Major Geeks, but nothing. It seems like this is a somewhat different problem than just the driver.

Incidentally, I used the system with sound fully operational last night and left my laptop closed in sleep mode overnight. I used the system briefly this morning but didn't try anything that used sound. I noticed the problem around 6 p.m. this evening. I can't recall whether I used sound at all during about an hour on the system this evening before that. I didn't restart or load any new software before the problem.

Guidance welcome. Let me know what you need to know about my hardware and software.
Thanks.

 

Couple things I failed to mention:
As I said the system crashed when I attempted to reinstall the sound device. More specifically, BSOC with error referencing rtkvhd64.sys
Found some online advice on this issue, suggest reinstall of Intel sound controllers. That didn't work for me either.

 

I saw a similar problem on here, a short time ago, and the poster eventually found that the system was looking for the wrong output - I gather that the poster found it was directed to hdmi, and of all things he used an old tv screen with hdmi to get his sound-I did not follow that further, but it leads me to suggest looking at the sound,and see what it is trying to use-See what the default device is.