You have to say more - It's a gas boiler - yes? Or Oil perhaps.
Comb or regular? (Is there a hot water tank)
Make & Model
What is "a bit"? How long?
What do you do to get it going again?
Water is - water is what?
You may have to call in a boiler specialist - and this is their busy time - avoid British Gas is my suggestion...
Good Luck...
December 2015