I was recording with Audacity, and everything was going great, and then I put one of the tracks on “solo” and the playback completely ceased. Every time I press the space bar or the play button, it doesn’t play. The button looks activated but the cursor doesn’t move and neither does the timecode. I also tried opening various files and they open very slowly and don’t play either. I’m using windows 8.1 and have audacity 2.0.5 I believe. 
Help!
If you do that, only that track will play.
If you have got dozens of tracks Audacity will respond very slowly.
Try rebooting the computer and run fewer other programs and services. Be wary of services that use the sound card like Skype.
Gale