Dude won't give me my hat back?

Alex
This dude I used to mess with/thought we were gonna date had sex w/me then cut off communication with me w/e and so I asked for my hat back bc I'm done with him. He told me he would give it back to me but whenever I try to text him and ask for it back he ignores my messages. Like it would definitely be breaking and entering if   I went and got it back myself but I don't know how else to get it back. I know it's just a hat but it's my favorite hat.