My combi boiler stopped working completely and the warning light that lit up on the boiler panel was relating to a problem with the air pressure switch I think... anyway I was going away that day, so left it until I got back having left it switched off from the electricity power....switched it back on and it has worked for hot water..not tried it for central heating obviously as a bit warm. I know I need to get it checked out but any advice prior would be helpful..Thanks.
Sounds to me like you've lost water pressure in the system (chances are the gauge which shows pressure in "bars" is below one). You should find a small tap below your boiler which is on the cold water inlet. Just open this up and watch the gauge rise until it's about one and a half to two bars. The warning light should go out.
not quite sure where mrs nording has got that one from but air pressure has nothing to do with the system pressure whatsoever.
you always have to take those warning lights with a pinch of salt as they can lead you up the garden path sometimes. I would carry on using the boiler as the light could be a one off and it may run ok but if it does keep playing up then call someone out.