Many things can cause outdoor lights to stop working including a blown fuse, a tripped circuit breaker, a bad connection, or a defective light fixture.

Outdoor lights stop working because of several reasons: 1) The bulbs may be burned out. 2) The light fixtures may be dirty or corroded and need to be cleaned or replaced. 3) The wiring may be faulty and need to be repaired or replaced. 4) The controllers may be malfunctioning and need to be repaired or replaced.