m class 2004 drivers door

[1madtrucker]

Hi i'm new to forum but I hope you can help please, my m class 2004 diesel drivers door wont lock with the remote or key, the interior lights don't work on this only so when opened alarm doesn't work, if I use the key the button on the door moves down but won't will not stay down, is there a sensor inside the door which tells the car the door is open or shut, hope somebody can help me thanks Andy.