Can spark plugs keep your car from starting?
Unless your car is a diesel, they can certainly keep your car from starting if they're missing. They can also become fouled or badly worn, which, again, could keep your car from starting.
It depend on the Cylinders... For example, If a car has; 4 cylinders it has 4 spark plugs 6 cylinders it has 6 spark plugs 8 cylinders it has 8 spark plugs Sometimes there are 2 plugs per cylinder. Such as the Ford 2.3L 4 cyl has 8 plugs and the new gen Hemi's from Dodge have 16 plugs on a V8 engine.