Why doesn't my Audi A4's engine start?

My Audi A4's engine won't start and I've checked the battery, fuel, and engine oil levels. What could be the issue?

It is possible that the issue lies with the starter motor. Check for any clicking noise when you turn the key in the ignition. If you hear clicking, it could indicate a faulty starter motor.

In some cases, a dead battery may still have enough power for the lights and other electrical components to work, but not enough to start the engine. Try jump-starting the car or replacing the battery.