1. Check the Obvious:
* Battery: This is the most common culprit. Check the battery terminals for corrosion. Clean them with a wire brush if necessary. If the terminals are clean, try jump-starting the car. If it starts with a jump, your battery is likely dead or weak and needs replacing or charging.
* Loose Connections: Inspect all battery cables and connections to make sure they're securely fastened. A loose connection can prevent the car from starting.
* Fuel: Does the fuel gauge show you have gas? If it's low, try adding some fuel. A completely empty tank can sometimes cause issues.
2. If Jump Starting Works (Battery Issue):
* Charging the Battery: If jump-starting works, your battery needs charging. Use a battery charger to charge it fully. If it still has problems after charging, it might be time for a new battery.
3. If Jump Starting Doesn't Work (Beyond Battery):
* Starter Motor: A failing starter motor can crank slowly or not at all. This requires professional diagnosis and repair.
* Alternator: While the alternator charges the battery while the engine is running, a faulty alternator *could* contribute to the problem if it wasn't charging properly yesterday and completely drained the battery overnight.
* Security System: Check your car's key fob and make sure the alarm system isn't engaged. Try different keys if you have them.
* Fuel Pump: A faulty fuel pump won't deliver fuel to the engine, preventing starting. You may hear a buzzing noise from the fuel pump when you turn the ignition key (listen carefully).
* Ignition Switch: This can fail, preventing power from reaching the starter.
* Fuses and Relays: Check the fuses and relays related to the starting system in the fuse box (refer to your owner's manual).
* Immobilizer System: The car's immobilizer might be preventing the engine from starting. This usually involves a problem with the key or the system itself.
What NOT to do:
* Keep cranking repeatedly: This can drain the battery further and potentially damage the starter. Try a few seconds of cranking, then pause for a few minutes before trying again.
Next Steps:
If you've checked the obvious and still can't get it started, it's best to:
* Call a trusted mechanic: They have the tools and experience to diagnose the problem accurately and repair it efficiently.
* Use a roadside assistance service: If you have roadside assistance, they can come and jump-start your car or tow it to a repair shop.
Don't try to diagnose and fix complex problems yourself unless you have significant automotive experience. Improper repairs can lead to further damage and costly repairs.
