#1: Initial revision
<blockquote>While electrons have positive and protons have negative charge. They should collide and vanish, shouldn't they?</blockquote> No. They have other attributes than just being packets of charge. You have to consider mass too. That mass (or you can think of it as the equivalent energy) doesn't just disappear. Some combination of mass and energy that sum to the original must remain. The total mass-energy of any photon produced plus remnant particle must be the same as the mass-energy of the starting particles.