1) When I played a video on Youtube with Firefox via my computer speakers, they worked flawlessly. 2) Then I plugged in my headphones via the headphones jack, there is no sound. 3) I went to Windows settings and checked the volume mixer and tested the sound, the headphones worked. 4) I opened Edge and played a video on Youtube, the headphones work flawlessly. 5) I played a video through my media player, the headphones work flawlessly. So my conclusion is that it is Firefox that is broken. I closed Firefox and restarted it and tried steps 1 to 5 above, still got the same results. Firefox did not play any sound over the headphones while all the others worked flawlessly. I restarted my computer and tried the steps again and still got the same results. I also deleted Cookies and Site data from Firefox settings and still no luck. Any suggestions?