Mine did exactly the same on Friday. The timer had stopped working. I did ring the company and they suggested changing batteries in the timer. I couldn't find anywhere on mine for batteries to go, but yours might have them. I found a switch inside the airing cupboard labelled "mains boiler" which i have now put on and the heating, hot water and timer are now working. However, I'm not sure if that switch is supposed to be permanently on, the TV has switched off a few times and I'm wondering if it's overloading something. But yes, look for batteries, pressure (red and black hands should be at the same place) and check fuses and switches first.