Why do I have no tailights

Start with fuses and relays. Pull each one and test it and/or visually inspect them. This is often the common cause of lights failing to work. It is also one of the cheaper methods for process of elimination. If all fuses and relays are in good working order, a small investment at an auto parts store is a testing kit. Basically a couple of fuses that ping to ensure power is getting to the lights in question. It is possible to have a short or a total wire disconnection between the power source and the light. And you can ask most auto parts stores for assistance in testing too. Hopefully this helps you in some way.