Brake lights, running lights, and turn signals.

Hope you can help. I have a 2002 Chevy s-10. The brake lights, running lights, nor the signals in the back are working. We have replaced the turn signal switch and everything. I took it to my mechanic and he wasn't able to finish checking it before he was hospitalized. Do you happen to have any recommendations to what can be wrong with it. I have checked/replaced all fuses. Please help if you can.. Thanks!