Although I am not very familiar with your model RV, I assume there is a junction box which contains the wiring which supplies power to the slide-out. It is possible the movement of the slide-out has damaged or disconnected the wires in some fashion.
Assuming you have checked the bulbs in the lights, first check to see if you are getting any electrical power to the fixtures. If the first light in the circuit has a bad connection, the rest will not work either.
If this checks out okay and you are getting 12 volts from the connection in the breaker or fuse box supplying the slide-out, then the bad connection would seem to be in the junction box. It may be necessary to contact the maker of your RV, or an RV service center to ascertain the location of the junction box.
Using a multimeter will help you track down the broken circuit much easier and will save you time too. Good luck!