My Ex won't give my Hoodie

Okay i have a guy friend who lend his hoodie to his gf but currently his ex. She broke up with him and won't give his hoodie back and stole other shit too. I'm trying to help him and he's pissed cause its a reallt nice expensive hoodie. Any suggestions what we can do to get it back or soemthing. I need him to have some backbone and to not just let her step all over him. oh and she's pissed cause he's already over her. But she's the one who broke up with him.