my mercedes cla radio is locked. Where can I find the radio lock?

To unlock the radio on a Mercedes CLA, you will need to use the car's audio key code. This code is specific to your vehicle and is required to unlock the radio if it becomes locked.

Here is the general process to retrieve your code and unlock the radio:

1. Locate the audio unit, which is usually found in the center console or dashboard of the car.
2. Press and hold the "AS" button on the audio unit.
3. Turn the ignition key to the on position.
4. Release the "AS" button.
5. The audio unit will display the audio key code. Write it down or memorize it.
6. Press and hold the "AS" button again and turn the ignition key to the off position.
7. Turn the ignition key back to the on position and release the "AS" button.
8. Input the audio key code using the audio unit's buttons.
9. The radio should now be unlocked and ready to use.

Keep in mind that the process may vary depending on the model, year and options of the car, it is recommended to check the car's manual or contact the dealership for more information.