"No sound" solved by quiting BIAB and restarting it. I got no sound on playback of a song. But another DAW was able to produce sound. Closed it.
Saved my current BIAB song as Midi file, closed BIAB and played the Midi just fine using Windows Media Player.

When I re-opened BIAB and played my song, I could hear it. No settings changed. I had simply re-started BIAB.

This suggestion isn't in the FAQ and should be added to the file at http://www.pgmusic.com/tutorial_bbw_nosound.htm

I use Windows 10. I had left BIAB open for over a day with the computer going to sleep more than once. It's a quirk of Windows 10.