baxi genesis 80 c/heating woking but no hot water?

I have a baxi genesis 80 c/heating combi boiler , it had been off for a few months. on start up I could get the c/heating working fine but there is no hot water . No water at all comes out of the hot taps .When hot water only is selected the burner does,nt fire up nor is there any water coming out of hot taps.