My brake lights and blinkers work but both my taillight went out at the exact same time. whats wrong with it?

If your fuse is out, the front marker lights would be out too. There is one single wire that runs both rear taillights, so I would guess your problem is most likely there, if it's just those 2 lights that are out. The chances of both bulbs going out at the same time is extremely low. Most cars also use the same ground circuit for both filaments of those bulbs, so the problem is not likely to be there. If you let me know what kind of car (year, make, model), I might be able to tell you what color of wire to look at.