my baby z 4 months old .she is cheerful all day and playful but after 9 pm she feels irritated and cries.wat might be d reason and how can she b happy?

Hi. It may be colic. Please consult your pediatrician to be safe.

Your baby may be simply tired and sleepy. A baby who has been awake long hours can get irritable and cranky. Evaluate her schedule and incorporate a short nap in the evening.