Whoa, the key is mechanical and will unlock the driver's door even if the battery is dead.

Is this a fairly new car for you? Check the key with the glove box lock, if it doesn't work someone may have changed the ignition tumbler from a junk yard car.

Or, the driver's door lock failed. There is a metal lever that gets pushed/pulled with the handle lock which may have fallen out??? Open the door and pull off the small black plastic cover near the top of the door jam. Shine a flash light in and look for a metal rod.

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Keeping it running is better than buying new