You’ve got a bigger problem than spark. Why didn’t you tell that in the first place? You need to make sure that you haven’t bent the valve on the rocker arm that’s loose. Try rotating the crankshaft to see if it can make two full rotations without locking up. If it works, then you reset the crankshaft so it’s at top dead center and readjust the valve with the loose rocker arm. If you don’t know what top dead center is (TDC), look it up.