1. The starter solenoid is not engaging. The starter solenoid is an electrical switch that connects the starter motor to the battery. If the solenoid is not engaging, the starter motor will not receive power and will not be able to turn the engine over.
2. The starter motor is damaged. If the starter motor is damaged, it may not be able to turn the engine over even if the solenoid is engaging. Starter motors can be damaged by a variety of things, including excessive wear and tear, overheating, or electrical problems.
3. The flywheel is damaged. The flywheel is a heavy metal disk that is connected to the crankshaft. The starter motor engages with the flywheel to turn the engine over. If the flywheel is damaged, it may not be able to turn the engine over even if the starter motor is working properly.
4. The ignition switch is damaged. The ignition switch is the switch that you turn to start the engine. If the ignition switch is damaged, it may not be able to send power to the starter solenoid.
If you are experiencing this problem, it is best to have it diagnosed by a qualified mechanic. They will be able to determine the cause of the problem and recommend the best course of action.