Why wont my left headphone work?

Why wont my left headphone work?
Ok so, I tried to use my Powerbeats pro so I could do schoolwork on my computer, but I quickly realized my left headphone wasn’t working. When I was trying to reset them with the B button, the button wasn’t clicking, but could still be pressed. Does anyone know why this is happening? Please give me an answer on how to fix this. Thank you.

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