what can I do for the best sister?your advice can save shes life?

Well,I have one sister,the kindness person that I knew,she is beautiful,smart,understand me and support me always.The family of my mother had so beautiful and kind,and my sister is like them.

She went to Germany for study,and something happened there,she come back,very sick.She never get out of the house,she think rarely that is the daughter of...queen of England...and other things.She don't accept medicines,or counselor,she think that she is ok,health.

I try to ask what happened there,and she said that something very bad,but never said what.

Our childhood was very bad because of violence of our dad,and my sister suffer more than us.She is now 40 years...

My mother put every day shes medicine in shes food,the medicine who the doctor said that it must to take.She is better in time,but

is so hard,what else we can do?