Parent Won’t Let Me Retrieve My Belongings From Their Home

Alright so, I’m 17(18 very soon)and recently got into a big dispute with one of my parents(A). We’ve had ongoing issues with each other for a long time. My parents are divorced and I am now staying at the other parent’s(B) house. I’ve decided I going to stay here full time now but I foresee one issue, that being parent A is quite vindictive and I’m growing concerned that they aren’t going to let me come get my belongings out of their house. The things I’d like to retrieve consist of, a bed, clothes, hygiene products/cosmetics, small sentimental items and a couple other random things. All of these I have bought myself, besides some small gifted items. I’m wondering what legal actions I could take to get my things in the event that, that happens. Could I contact local law enforcement or would I have to involve the court? I live in New Hampshire. Any advice would be appreciated, thank you! :)