What Causes Lack Of Memory In A Child?

my brother daughter who is 7 years old she is not remembering any thing last year she studies in UKG again the school they cant give promotion to her and again they ask us to continue with ukg. She wont listen any thing what ever we do with her some times bro. beat her then she will listen after some time she behave same. i am bit tense to think that her mind getting devolpe with her age or not.