If you don't speak can your vocal cords atrophy to the point that you completely lose your ability to speak for the rest of your life? if so, how long would it take to lose it?

This is not likely to happen. Speech therapists can work with a person and strengthen the voice and the muscles needed to produce a voice so that permanent loss of a voice would not happen. Good luck!

There are numerous religious orders around the world whose members have stopped speaking due to vows of silence and none of the members lose permanent expressive speech ability. The vocal cords do NOT atrophy secondary to silence. Do not have a clue as to why you have asked this question, but you can repost your concerns and we will address.