WAV and MP3 not playing in Windows Media Player

When I create a WAV or MP3 file and try to play it in Windows Media Player, I receive the following error message:

Windows Media Player cannot play the file. The Player might not support the file type or might not support the codec that was used to compress the file.

I’m using the default settings of Audacity 2.0.3 (from the exe installer). The files will play in Quicktime Player.

Please post a short (just a few seconds) example of what you are exporting.
See these posts for how to create and post a short WAV file:

The problem has been fixed. How, I don’t know. It just started working again. Thanks for the help.