my baby boy is now 2yr 3 months old.he was able to speak n tell alphabets numbers n around 10 rhymes till the age of 2 yrs.since last couple of months ,he became very silent and play with himself .though he remember all the rhymes n all he is not speaking out.he doesn't respond to us and he stay in his own world .but he is active in all terms. my question is that is it normal to have kids forget or ignore what they have learnt? does play school help him break the silence? as a mom , what are the things I can try to make him speak n respond?