My key will not turn the car on.
There are many questions that should be answered before diagnosing this type of question. Does the key not turn the ignition, or does the ignition turn but the engine will not crank, or does the engine crank but with no start? These are questions that would have to be answered before the vehicle can be diagnosed. I recommend seeking a certified mechanic, such as one from YourMechanic, to come and test your vehicle’s key ignition to determine what repairs are needed.