Sounds like a broken wire somewhere in the field
Do you have a multimeter?
Ohm out that valves by touching the particular valve and the common, if you don't get a reading or an infinite number then you have a broken wire somwhere
As a tech, my next step would to simply wire trace out the line to where the break is, this may be more difficult for a homeowner. I know you can rent wire tracers, it may be easier to install a new wire from the controller to the valve box?