Welcome back. Hope life calms down for you soon.
Two things.
1) What kind of audio file were you playing? MC does not support visualizers when playing back Quicktime media, including M4A (unless you are using DirectShow to handle those, which is why DirectShow is better). So, if you aren't using DirectShow and you're playing something which uses Quicktime, it'll work just like that.
2) Assuming it was just a MP3 or some such thing, and you should have the Visualizers. What are the contents of: C:\Program Files\J River\Media Center 12\Visualizations
Did they somehow get deleted? Perhaps a full uninstall/reboot/reinstall?