What caused my running lights to quite working?

I have a 1996 Dodge Dually 5.7 liter diesel. I went to go somewhere in the
evening and after starting the truck, turned on the headlights, went to open
the gate and upon returning to the truck, realized I had no tail lights, no
marker lights.  When I stepped on the brakes they do light up, but that's it.  
Dash lights do not work.  Also when I try to plug in for trailer lights, they
don't work either.