my child is 19 months old and i did not understand how to deal with him because he is not listening his behaviour totally changed i do not what to do.

A. Look you have to understand the difference between not responding naturally or not responding by his choice because in this age kids do not have sense of not responding by choice so it would be good that first you get it checked with a specialist to know if there is a delay in understanding of your child and accordingly they can guide you further