I want to know how to totally reset the crank /CAM pulleys and the injector pump

Unfortunately our reference material doesn't have a listing for the Fiat since it's not available in the U.S. If it's anything like engines I'm familiar with, there will be a small dot or triangle on the crank and cam pulleys that need to point at each other. Your engine, from what I could find, is an interference type. This means if you crank it over with the starter with the belt slipped or broken, you can cause serious damage to the engine. Turn it by hand.