Same issue after updating - no audio devices installed!
Spent ages trying to fix it, using the troubleshooter, playing around with drivers, rolling back, updating - but nothing worked til I stumbled on this!
A quick fiddle with the ease of access options and my onboard Realtek sound and Nvidia HDMI audio is restored. It doesn't seem to work if I leave Windows running for a bit then decide I'd like my audio back, but just after boot each time, it's fine.
Microsoft - please fix this.
Known issue, easy fix! NO need to restart the PC again.
I gave the fix a bit back in the thread.
IF you tinker with Ease of Access but sound devices do not come back, try this:
Open the Windows 10 OS Services console. Now locate Windows Audio service, right-click it, click Restart - confirm all prompts.
Then go back to Sounds, Ease of Access and now sounds should come back.
Please tell me if that works, or not. Please tell me if something is not clear.