Shit, if I stole my dad's girlfriend's son's laptop, I wouldn't be here typing this comment on it.

Steal it back. He's TEN, it's not like you're trying to outwit VOLDEMORT.

Wedgies/swirlies/noogies are middle ground. Not too violent, but painful enough to teach the little shit a lesson.

Figure out what the boyfriend and his son‘s full name and telephone number and address are and call the police department nonemergency number and tell them what is happened and if you can provide model and serial number of your computer. He has committed grand larceny 3rd degree which is anything over $3000 which is a class D felony punishable by up to seven years in prison. As a kid is only 10 to boyfriend is on the hook of it. They will take it seriously and contact them.

Hire a 10-year-old bully to beat the shit out of the thief and retrieve your computer. If you have enough money that you can piss away $4K on a toy, you can afford to entice some prepubescent thug to do your dirty work.

how old are you? did your mom buy it for you that's why she doesnt care? do they live with you guys?

I read that as your mom's boyfriend stole it and skipped the son part. So when you said he was 10 I got really confused

Steal his stuff

Just take it. It’s yours. Don’t let it bother you if the little thief starts crying. Just take it back.

Does your mom not speak the language of money? I mean it's a $4000 laptop. Not some $20 action figure you can spare. And don't you also need your laptop for school/work?