My Mum sold my dog 5 years পূর্বে when i was 7 and i just found out as a 12 বছর old. How can i get the dog back???

If your mother was the official owner, and I suppose she was because আপনি were seven and not an adult, and she sold it with all the paper there is nothing আপনি can do against it per law. আপনি could only ask the owner if he would sell it back but after 5 years I doubt so.
Sorry আপনি can't do anything because it was the dog of your mother, so it was her decision and আপনি weren't old enough to decide for yourself if আপনি were the official owner, but I doubt that too because আপনি were and are to young to buy a dog on the paper

Hi aleks, i am going to be honest with you, but after not having the dog for that long আপনি can't get it back unless the সেকেন্ড owner gives it away. So if ur parent gave all the papers to the সেকেন্ড owner, আপনি can't unless আপনি contact the AKC অথবা ask someone. But i'm sorry but আপনি can't get the dog back unless there's a reason tbh. And i actually do agree আপনি might have been to young for the dog and she didn't want আপনি to own it yet cause u were 7. My বন্ধু in real life actually had something similar to ur problem were his mum ব্যক্ত hes going to summer camp, 3 years later we have kept him since.So we could give him back but hes a good boy so we always send pics of him. Again i'm really sorry for not being able to get him.