Picky Eater

Help! My son used to eat everything and now has become very very picky. (He does eat all fruits but not all vegetables, and the only grains he will have are like waffles and Ritz crackers, sometimes rice, sometimes pasta) but more times than not he will just play with the food. Is there anyway I can try to reintroduce the foods or something because it’s not like he didn’t enjoy it before but somewhere along the way he stopped eating all the actual Nutrient filled meals.