I think my friend stole my money , how do I get it back?

The first time I went to her house I lost 20 bucks that I was pretty sure my friend stole it. But I just convinced myself that I lost it. But yesterday I went to her house with 75 dollars in my wallet from my birthday and now all of it is gone. I need to find a way to get my money back. An if I confront her, she sure is not going to give it back. All I want is my money back then I'll end my friendship with her.