Sound won't work, but everything else does.

I was using audacity on my desktop one day and it wouldn’t playback sound. Audacity will play it, the bar of the left and right channels work, just no sound. Everything else works fine. I can record (with sound), amplify, and things like that, but if I want to hear it, I have to export it as an MP3 (although I sure the other formats would work fine) or play it on the laptop which has audacity and works fine. Any ideas of what’s gone wrong and how to fix it. I want to get this out of the way as I might add a 4 Channel PCI Sound Card for multi channel recording.

Did this happen right after you plugged in your USB turntable or other USB device?

Audacity has a drop-down device manager where you can tell it where to put the sound so you can listen. It can get reassigned by accident and get lost. It’s not unusual for Windows to try and send sound to a USB turntable in addition to getting music from a turntable. No, that doesn’t work very well.