Was there any work done on your lawn this month? Can you manually turn the zone on from the clock? Can you manually turn the zone on from the valve? Do you have a manifold assembly with multiple valves in the valve box, or is each zone valve in it's own seperate valve box?
Turn zone one on from the clock (controller) for at least ten minutes. Go to the valve box and remove the wire nuts from one of the wires going to the solinoid for zone one. remove the wire connection. Touch the wires back together that you just pulled apart. If you can hear the clicking of the soloinoid, the clock is fine. That means that you are getting power to the solinoid and also that the solinoid is working.
Mick
Irrigation Contractor
Certified Backflow Assembly Tester