Viessmann boiler heating water but not rads

I have a Viessmann boiler with four pipes coming from it, the two centre ones seem to go into the tank in the hot press and are hot. the outer left and right are cold. There doesn't seem to be any heat going to the radiators. It was working two nights ago. any ideas what it could be?

thanks

Does it have a multi (at least two) zone controller attached. If so maybe the zone for radiators is turned off.

The controller has a control for the water and the radiators. Don't think there's zone control. there's a thermostat beside the controller, when i adjust it down i hear a click as though it's trying to turn the heating on.

i press the reset on the boiler when i got home last night and tried it again. It worked. Must've been something on the boiler

thanks for your help