Why is my tortilla turns crunchy and breaks whn i roll it?

The simple answer is that however you are heating them up, you're doing it too long. Corn tortillas should be fried in hot oil for 15-20 seconds per side, then drained on paper towels; and flour tortillas should be heated on a grill or in a hot dry skillet for the same time. If baked in some sort of cerole, be sure to cover the dish with foil, and remove it only for the last few minutes if you're trying to brown the top.