Have you checked your breakers in the panel inside the door. If they are fine there could be a possibility they are not hooked up. Also there could be a GFI that has tripped that may feed those plugs. I would check the breakers and GFI ' first. If that does not work you will have to take the bed off and start tracing the wires from the plugs back to where they connect.
2015 36RL pushing a 2015 Denali