Why won't she give me my stuff back?

I had a friend living with me for a long time, things got bad and she moved out. I had some of her stuff that I returned to her nice and washed and not ruined at all. When she came to get the rest of her stuff (dresser, bed frame and such) I asked her to bring the stuff of mine that she took back to me. She stole clothing items out of my room when I was gone and I specifically asked her not to go in my room. I have asked her a lot of times civilly to bring back my stuff and she just ignores my texts and calls, claiming that she is being mature about the situation. She also put a bloody pair of underwear (still wet) in with a drawer of my stuff (spare cell phones and some other electronics) getting her blood all over them. What can I do to get my stuff back since she's not responding? She brought back one pair of my white pants that she ruined and got black all over them. Everyone keeps telling me to let it go but I can't. She has always stole stuff from people and I'm tired of it. She has a very expensive pair of pants of mine, three shirts that were about $40 each and some other little things that start to add up. What's your advice?