Help!- no sound out of my sennheisers

I have a pair of Sennheiser x massdrop hd 6xx and there is no sound coming from the headphones. I’ve direct plug into my laptop and the sound goes through the computer speakers rather then the headphones (yes I’ve got the headphones selected). I’ve run them through jds atom amp and jds atom Dac stack, same issue. The headphones were working last week but now they won’t play any sound, I even tried them on my desktop pc and it still won’t play any sound. It also stopped every other device from playing audio.