3 way switch that stopped working
I'd have to go with the ballast of the first light (that switch 1 runs to) has died and needs replacement. However, tube-fluorescents have terrible socket connections and I've seen earthquakes, rumbling trucks, direct impacts and power surges kick them askew.

If you have tubes, then start with number 1 in just giving the bulbs a little twist to see if they pop on...yours may work in pairs-only, so you get one to flicker and then twist the other to get them both solid.

If so, then just do the same to the other 2 fixtures. If not, then a new ballast should remedy the situation.