Car does not start

I assume you mean the starter does not even crank the engine over. If so, to begin, check the battery terminal connections, starting right at the battery. Try real hard to twist both battery terminal connections and if either move any at all, it is too loose. If okay, check the negative battery cable ground for being loose and the positive battery cable being loose at the other end toward and/or at the starter itself, then go on to checking all the fuses starting with the main fuses.