two options - most likely a valve has been turned off accidentally?
if it is a system boiler and cylinder, make sure little hands have not been at work in the airing cupboard.
Follow the flow from where the hot water should come from, to where it should come out whilst looking for any means of isolating the supply.
no other reason why you should have hot in one area and not in another unless you have an uninsulated frozen pipe under the kitchen floor for instance.
bubblehead, January 2010
