19 months n still not talking many words n Not speaking in sentences . Should I be worried ?

Nothing to worry. My son is 22 months. Still saying only few words like mummy, hai, bye etc... Sometimes he is trying to talk in new funny unknown language, without any meaning. It's all part of learning. Try to talk more with ur lo. Tell him stories, so slowly ur toddler will try to imitate ur words. If possible, expose to more kids for example take ur lo to park so by observing others ur baby will learn more.