I dont know what to suggest im afraid. I wouldn't worry much about him not urinating if he's not drinking either.
Puppies can be off their food for around a day and this is perfectly normal in most cases, if it goes on much longer then you should seek advice and contacting your vet just to be sure is a great idea.
Also, if your pup was used to another type of food before you had him then he might just be a picky eater and not want to eat anything but what he had before. In this case you should try and slowly change the food type to get him used to another because puppy stomachs can be fragile and changes may cause diarrhea and vomiting.
If it hasn't been too long then dont get yourself too worried, puppies are known to be off their food now and again.
