I had a similar problem...... it looked like sound was working in Windows 10, but there was nothing coming out of my speakers.
That was just one problem with my initial install. There were several, like the time zones only showing the Pacific Time Zone.
I never could get Win-10 to boot up without stopping for a password, so I finally decided to bite the bullet, so to speak, and just start over with a Clean Install of Windows 10 to a new (spare) hard drive.
During the install, I finally figured out I could complete the install without ever putting in a password. Then once the install was complete, I was able to set the time zone correctly and I was elated to find I finally had sound, not from my PCI Sound card, but form the On-Board sound chip, on my 10 year old motherboard. Eureka! Success at last! Now EVERYTHING works.
I still don't know what went wrong with that first install, to a spare HD, but something sure did. It was a mess.
So if nothing else works, RE-Install and start over. That's why they call it Beta TESTING! TESTING being the key word.
Nobody is actually RUNNING Windows 10, yet, because it's not even been released in its final version.
Good Luck!
TechnoMage
