I think my bestfriend stole my physics notebook, I know its weird but how should I check it?

Our colony takes studies as a competition , and my bestfriend is very competitive and she is even better than me in studying but in a recent national level test I scored better than her. After that test her attitude has changed too! She has become very selfish , she was before too but now it is way too much. She doesn't solve doubts of anyone like she just solves it for herself but doesn't share the answer. I had also called her at my house to teach me something and I guess my physics notebook was nearby the desk. I had also gone outside of room 3 times. Ever since then the notebook is lost. I have checked everywhere in my house and now I suspect her. What am I supposed to do? can't even ask on text or face to face cuz she pretty good liar, should I just barge into her house?

I think my bestfriend stole my physics notebook, I know its weird but how should I check it?
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