To unlock it:
1. Insert the key: Make sure you have the correct key for your vehicle.
2. Turn the key: Turn the key to the "ON" position (all the way to the right, usually past the accessory position). This should unlock the steering wheel. If it's very stiff, gently jiggle the steering wheel back and forth while turning the key.
If the key doesn't turn:
* Check the steering wheel: Ensure nothing is obstructing the steering wheel's movement (e.g., a stray object).
* Battery: A weak battery can sometimes prevent the ignition from turning. Try jump-starting the car.
* Ignition switch: A problem with the ignition switch itself is possible, though less likely. This would require professional repair.
* Steering column: Less common, but possible mechanical issues in the steering column could be at fault. This is also a job for a mechanic.
* Key Problems: Make sure your key isn't damaged or worn.
If you've tried turning the key and gently moving the steering wheel and it's still locked, it's time to consult a mechanic or a locksmith. They can diagnose the underlying issue. Do not force the key or the steering wheel, as you could damage the ignition system or the steering column.