Snowy Blossom

Then you'll have to report it to the police as a theft.

Sorry, chimed in here. I can't tell if you are talking about your family doing anything to your collection or the neighbor. Technically nothing can be done if was your family unless you are over 18 because they own what you 'own'. If it is the neighbor and he refuses to give it back, go to the police and follow a theft report. You will most likely need proof of purchase of some kind so be prepared for that. Message me for more details if you need it.

He's 24, his parents should have no say in the matter