Year make model would help but heres a guess.
You have a short on the wiring. The most common area is the tail light socket. If it's a light that is in the trunk lid check the harness where the wire goes from the body to the trunk lid as the wire tends to flex there a lot & break.
Bulbs may be blown.
Check for any blown fuses or burnt out light bulbs.
check your ignition switch.
You may have blown a fuse. Check your fuses. Then you can check your light connections.
the fuses are located on the inside panel next to the drivers door ,there is a diagram showing what all the fuses are for.are you sure you have not a dud bulb.james
As you open the drivers door there is a panel marked fuses. It is labeled in there.
sounds like a blown fuse,check all fuses with a fuse tester replace any fuses that dont light up
== == Under the bonnet next to the battery. It is located in a black box, once cover is removed replace all blown fuses with correct fuses.
any advance auto will
Check the fuses, if the fuse is blown you may have a short in the running light circuit.
Check your fuses. One is probably blown out. If that is the case you might check the trailer light hookup if you have one.
Could be a bad ground or bad wire leading to the tailights possibly a bad brake light switch.