Manual override should turn lights ON-OFF even if timer has gone bad.
It sounds like problem is electrical.
Test that timer is getting electricity from breaker.
Burned out bulb. Change bulbs. Spray WD-40 on bulb threads before installing bulb.
Outdoor wiring can go bad easily, outdoor bulb sockets become dirty and stop functioning.
Loose wire between breaker and timer -or- between timer and lights.
Loose wire inside timer box. Tighten screws.
Loose wire on circuit breaker. Tighten screw on circuit breaker.
Tripped circuit breaker: click circuit breaker all the way one direction and then all the way back other direction.
Bad circuit breaker. Move wire from one breaker to another same-size breaker.http://waterheatertimer.org/How-to-replace-circuit-breaker.html
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