MIDI Troubles

Does anyone know what to do about the following?

For some reason, I lost all the sound on my MIDI files. There cannot be nothing wrong with my computer's sound since my Windows Media Player still plays MP3s and other audio-related file types. It's just that the sound on the MIDIs is gone.

Is this just happening in ZC, or in all programs?

Never mind. I figured it out. My volume control showed that the MIDI device was muted.