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

If your mother was the official owner, and I suppose she was because आप were seven and not an adult, and she sold it with all the paper there is nothing आप can do against it per law. आप could only ask the owner if he would sell it back but after 5 years I doubt so.
Sorry आप can't do anything because it was the dog of your mother, so it was her decision and आप weren't old enough to decide for yourself if आप were the official owner, but I doubt that too because आप 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 आप can't get it back unless the सेकंड owner gives it away. So if ur parent gave all the papers to the सेकंड owner, आप can't unless आप contact the AKC या ask someone. But i'm sorry but आप can't get the dog back unless there's a reason tbh. And i actually do agree आप might have been to young for the dog and she didn't want आप to own it yet cause u were 7. My फ्रेंड्स in real life actually had something similar to ur problem were his mum कहा 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.