Somehow managed to mute mplayer and can’t figure out how to restore sound

I was randomly/experimentally pressing buttons while playing a video with mplayer. Something I did caused the video to mute. I then exited the video and tried a different one, but that one was muted too. I didn’t think that mplayer saved its settings across invocations, except for the settings in .mplayer, and I certainly did not save any settings in there, nor do I see anything in there now that could be causing this.