I am muslim boy and I'm 15 yrs old my sister is doing black magic on me so that I cannot concentrate on my stdies please help me how can I get rid of this problem?

Thank you

Ignore her. Black magic is only real if you believe in it.

But I have seen the effects so I told this if you can help me please help...
Thank you

Tell your parents to make her stop.

But really, you believe in it, so it works, you were told, so now you worry and believe you can not do your studies.. if you ignore her and accept the fact that magic only works, if you accept it, then it can not work. It has no effect on those who will not believe in it.

It's called the power of suggestion, similar to hypnosis. If I could hypnotize you, I could tell you that the pencil in your hand is on fire and you would believe me so much that you would actually have a burn on your hand. You believed her, so it's 'working' on you.
Use your own power to make it go away and do well in your studies. And tell her you aren't afraid of her any more. How old are YOU?