If you recently upgraded to the latest version of BootCamp and audio is no longer working, you can try this:

1. Start the Device Manager
2. Expand Sound, video and game controllers
3. Right click on Realtek High Definition Audio
4. Select Properties.
5. Click the Driver tab.
6. Select Roll Back Driver.

This restored audio on my MacBook Pro. I couldn’t find any other fixes that worked — and this is simple.