Jeff brooks

I was attempting to change the light bulb right next to the doorway of the coach when I accidentally shorted the power wire. Now all my interior lights in the camper part are completely out under the 12 volt system but when I plug it into an outlet for 120 volts they work. So whatever it is called that switches it over between 12 volt and 120 volt (probably something like point contacts) are no longer allowing it to switch over to the 12 volt system. Can you tell me where and what I am looking for and is it possible to dismantle and repair said contacts or diode?