How do i fix my boiler (Vaillent)?

I Have just bought a house that was a reposesion the boiler has been off for about a year (Poss more) the boiler powers up but doesn't heat up water or raidiators there is water coming out of the hot water taps but it is as cold as the cold taps the boiler's fault code is f:22 which means there is no water in the system or the pump is broken. the gauge for water pressure is at zero and i have turned all stop cogs i can find in the house I have also shouted at it but this didn't seam to help any ideas?