Broken Knob controller

Hey! I bought a propane gas grill with 3 burners a while ago (I can not return it anymore) and while I was trying to assemble it, I broke the 3rd knob controller. As a result, the 3rd burner is not lighting on at all. Can I replace the knob controller somehow, or not? Is it fixable? What do i need to do? Is it just the knob or the whole burner for replace?