If the level wind has stopped working then it can only be two things.

Broken pawl cap and the pawl fell out or the pawl broke.

Broken idle gear. Pull the spool out and look for broken or stripped teeth on the spool. Also look at the now open space in the frame. You should see a white plastic gear check that for damage.

The only way that idle gear will break is if you got your finger stuck in the level wind or something is in the tracks on the worm gear (level wind gear). Shimano should repair it at no charge.