* Dead Battery (less likely given lights work): While the lights working suggests sufficient battery charge, a weak battery *might* be able to power the lights but not the higher-current draw of the starter. Test the battery voltage with a multimeter to be sure. It should be above 12.4 volts when the engine is off.
* Bad Battery Cable Connections: Corroded, loose, or damaged battery cables (positive and negative) are a very common cause. Inspect the cables at both the battery terminals and the starter motor connection points for corrosion, looseness, or breakage. Clean any corrosion thoroughly.
* Faulty Starter Relay/Solenoid: This is a very likely culprit. The relay acts as a switch, sending high current from the battery to the starter motor when the ignition key is turned. A bad relay will prevent this current flow, resulting in no cranking sound. You may hear a clicking sound from the relay itself *if* it is partially failing, but in this case, you're hearing nothing.
* Neutral Safety Switch (NSS): This switch prevents the car from starting unless the transmission is in Park or Neutral. A faulty NSS won't allow the starter circuit to complete, thus preventing the starter from engaging.
* Ignition Switch: A failing ignition switch may not be sending the proper signal to activate the starter relay or solenoid.
* Broken or Damaged Starter Motor (less likely but possible): While a bad starter *usually* makes a clicking noise, internal failure could completely prevent any action. This is less likely given the lack of any sound from the starter.
* Wiring Issues: A break in the wiring between the ignition switch, the starter relay, or the starter motor itself could interrupt the circuit. This is harder to diagnose without a wiring diagram and a multimeter.
Troubleshooting Steps:
1. Test the Battery Voltage: Use a multimeter to check the battery voltage.
2. Inspect Battery Cable Connections: Look for corrosion and looseness at both battery terminals and the connections to the starter motor. Clean any corrosion.
3. Check the Starter Relay/Solenoid: This often requires locating the relay (usually under the hood in a fuse box or on the fenderwell) and testing it with a multimeter or replacing it (a relatively inexpensive part). Some relays can be tested by jumping across their terminals with a wire, but be very careful when doing this!
4. Check the Neutral Safety Switch: This is usually located on the transmission. It can sometimes be tested with a multimeter, but replacing it might be simpler.
5. Check the ignition switch: This is more involved and might require professional attention.
If you're not comfortable working on your car's electrical system, it's best to take it to a qualified mechanic for diagnosis and repair. Attempting to jump across the starter terminals can be dangerous and further damage electrical components.
