Why wouldn't the rear turn signal and hazards work if the front works and so do the rear brake lights I have changed the rear bulbs with no result?

A break in the wiring for these circuits exists somewhere between the fuse panel and the rear assemblies. A wiring diagram would be useful in determining the point most likely for the break. The brake lights are on a separate circuit than the hazard flashers and the turn signals in many vehicles; and, the front indicators are a branch of the same circuitry which runs to the rear. The break in the wiring is downstream of this junction.