
You will ahve to start from scratch and remove all paper and clean the areas he wees with biological cleaning product to remove traces of it that a dog can still smell.
Take the puppy outside into the garden every halkf hour and using a comand word speak encouragingly until he performs and praise. Als take him out after meals, games, any excitemetn and on waking.
I have an 18 week old puppy who still is only just getting the hang of asking to go outside, but if the back door is open she will perform on command, and has trotted outside since she was five weeks old (as did her littermates).
Once he understands that weeing inside is inappropriate, and he will be praised for doing it in the right place, even pretending to wee, or just getting a few drops out when you say, so that he can earn your praise, and his body is gradually able to hold on for longer he will become clean, but don't expect this to happen until about 5 to 6 months of age, and expect the odd accident up to about a year.