We live in a detached bungalow with a combi boiler. We changed the bath and basin taps in the bathroom when we turned the water back on there's no hot water in the bathroom and no water at all in the kitchen!!!!!! can anyone help
Odds seem high that you didn't actually turn the water back on correctly, since the taps in the bath were what you worked on and the kitchen now doesn't get water which cannot be caused by the bath taps - but can be caused by not opening valves after closing them to work on the bath taps. Impossible to provide any more specific hint from afar, but follow the waterlines and recheck all the valves.
I suppose if the new taps were soldered on and you really went overboard with excess solder you might have plugged the pipes, but that's really reaching for a cause (i.e., seems not very likely .vs. just closing a valve you thought you were opening, or the like.)
Could it be an airlock? Try opening all the taps in the house until they all run freely. (possibly not all the way, as overwhelming the incoming supply would be counterproductive).
Do you know what sort of water layout you have? As you are referring to "taps" then I would guess a typical UK layout with a cold-water header tank that feeds the hot system that may also feed some cold taps. Typically any drinking water (kitchen and bathroom sink) will be plumbed directly to the mains and things like showers and toilets to the tank supply.
So, I suspect that you may have turned on the main supply but for whatever reason the tank supply is off. Either a stop valve you forgot, or a plugged outlet, or maybe the ball-valve in the tank has stuck. (easy to check)