firefox has no sound

i have used Firefox for years never an issue.

3 or 4 days ago the audio stopped working for no reason. the audio works fine on google chrome, Microsoft edge, video files but not on firefox?

autoplay is set to "allow audio and video" a youtube video plays but no sound. i did notice if i set autoplay to " block audio video" nothing happened, the video played yet no audio. volume mixer shows Mozilla firefox but no sound. what is going on, this is beyond me.