How do you lot cure zombie villager?

throw a name tag on it before you start if you can. zombie villagers can despawn like any other zombie, and losing one halfway through the cure after spending a golden apple is annoying.

trap it first. dig it into a two block hole or wall it in, otherwise it wanders off or burns at sunrise and you've wasted the potion. splash potion of weakness on it, then feed it a golden apple - the normal one, not enchanted. it shakes and rattles for a few minutes and then turns. keep iron bars and a bed near it afterwards and the trade prices drop right down.