Cant hear a track

I have a recording that has a stereo backing and a mono vocal track. When I open the project I can see both, but I only hear the vocal track. It was OK when I recorded it. It seems to have happened when I deleted all the duff takes of the vocals, so it looked nice when I next opened it. Nothing is muted (All three waveforms are blue).
Fortunately this is not a song, and I have the backing else where, so I can recover, but would like to know if I did something, so that I don’t do it again!

Any one got any ideas?

Never delete anything until you Export As WAV… to get your final show as a single sound file.

You messed up your Audacity Project. Projects are clouds of files that make up a performance when you press play (spacebar). The silly metaphor is somebody building a freeway just ahead of you driving and taking it up again just as you pass by. You saw a perfect road, but then you look back. Empty fields and trees. It will do that again and again as long as you never change the road crew.

All the original capture clips and segments are part of your Project. What you did was delete one or more sound files that Audacity was still standing on. Think clouds of files. Not one. The blue waveforms are, guess what, two different files in the cloud. That’s why the blue waveforms seem to be in grand shape even though the show’s gone. Only when Audacity manages its files and clips do all the files in the cloud get updated and managed properly.

You going in by yourself and trying to do it is just asking for trouble. There’s another joke that the compulsive people who “clean up” a lot get killed with this. Us sloppy Joes are fine.

Export As WAV… is the first time you get one finished sound file that you can email to your mum. You can’t email a project.