My scenes won't play anymore. Can only hear audio, but none of the animation happens. Doesn't progress through the frames.

Was trying to figure out how to adjust the volume of two different simultaneous audio files. Clicked "Convert to Keyframes" and now nothing works. It won't progress through the frames. I reverted back to a previous saved file, but now none of them work.Whenever I hit the Play button for any scene, I hear the audio, but it doesn't progress through any of the frames for any of the animation layers. Any help is much appreciated.