If there is adequate supply of gas, after the regulator, but none of the gas plates will light, then there will be a blockage in the system/gas line between the regulator and the cook top, more than likely. Hard to say for sure without looking, but that's what I'm thinking.
it has been working fine and was apparently left on low heat with the flame out when found, not sue about blockage, any other thoughts is there a shut off or reset ?
Other than the mains gas, check the gas line feeding into the cook top. If there is a valve fitted, you will see it as it joins up to the pipe that feeds the cook top. None of the plates will light>?
no plates are lighting i have had it apart and i think that it maybe an electric valve ?I cannot blow air through the pipe whilst the vavle is turned open
You can try switching it off at the power box(oven/cook top)and see if it resets the unit, it cant hurt. Maybe wait ten mins or so, before turning the power back on.
OK shall do thanks - next will be a warranty call