How do you reprogram a key for a 2000 Buick regal?

To reprogram a key for a 2000 Buick Regal, you'll need a working key and the vehicle. Insert the working key into the ignition and turn it to the "On" position without starting the engine. After about 10 seconds, turn the key back to the "Off" position and remove it. Then, insert the new key and turn it to the "On" position for 10 seconds. This should successfully reprogram the new key. If you encounter issues, consult the owner's manual or a professional locksmith for assistance.