sounds like your gfci located at the equipment is tripped , most installations use 1 gfci for both pool & spa light , if there is a problem with either light the gfci will trip, whereas the good light will not work either,
go out to your equipment area & look for a gfci, it may be in the breaker panel as a circuit breaker or more likely in a single gang box located on the side or below the box , you have them in your bathroom & probably the kitchen, looking at the face of the gfci you should see test & reset push the reset & then turn on either your spa or pool light if one comes on note which one, say the spa for instance comes on leave it on & turn your pool light on if it trips your gfci you know the trouble lies with your pool light , as a note during rains gfci's can trip this may be your cause ?