If it was twisted, could be the wire inside has twisted and broke somewhere. You did mention the beep from vent, are other people hearing it or just you? Could there be a mute on your headset somewhere that was switched? Sometimes I have seen with logitech headsets that happens and it causes alien crosstalking and other people hear stuff back at them instead of your mic when its changed. Other then checking vent or windows settings, headset cables tend to get twisted and go bad.