Lost the key to my Daewoo Leganza. What is the best solution?

Pull over to the side of the riad and place t in park "P".

Go to the dealership with your photo ID, registration, and title to the car. Using that information, you can prove who you are, and that you are the owner of the car, and they can use the VIN number of the car (on the title and registration) to look up the key code for your car. Then they can cut you a new one using a master key for that key code.