Check the Fuses, Fusible Links, and Ignition Switch
If the battery is in good shape, check for a blown fuse or fusible link. Check your car’s manual to find the location of the fuse box, then open it. With no power running in the vehicle, inspect the fuse for a metal wire. If the metal wire inside the plastic casing is severed or damaged, a blown fuse is preventing power from reaching the starter relay or solenoid.
You may need a fuse puller to remove the correct fuse and a light source to see its internal components.
If the fuses are in good shape, the car’s ignition switch is faulty. The ignition switch isn’t the mechanical part that you put the car key into; it’s the electrical switch that the mechanical part operates. In some situations, the ignition switch delivers power to the car’s electrical components but not the engine starter.
Diagnosing and fixing a broken ignition switch is more complicated than checking for a blown fuse. A good rule of thumb, though, is that if the instrument panel and dashboard do not light up when the key ignition is moved to the second position (between off and on), then there may be a problem with the ignition switch.
If you have a manual transmission, a bad clutch pedal position sensor can prevent the engine from turning over while allowing the electronics to work fine. The purpose of the clutch position sensor is to allow the vehicle to start only when the clutch pedal is depressed, so if it fails the car won’t go anywhere.