door lock question

[Sylvester]

hi.. i really need help my 93 mercedes 300se drivers door lock wont work with the key. it turns freely lock or unlock but locks from the inside and the alarm green and red light also not working with the key. but works with the remote what can this be, kinda sound like a cable come loose are something what do you guys think, are where do i start first i really appreciate your help thanks alot.