Why aren't my motion detector lights working?
Many models seem to be sensitive to power surges. A lighting storm or frequent episodes of lights flickering have destroyed several of my sensors over the years. Some models have a switch on the detector head. The switch may allow you to test the unit by placing it in test mode. If that option is not available you will have to disassemble the fixture and use a noncontact voltage tester to verify power is present at the fixture.