why is there no hot water coming from any of my taps?

H,i really hope someone can help me as i'm about to lose my mind!
I have had some problems with my boiler (although this is now working perfectly)..in the process of fixing the boiler i seem to have cut off the suply of hot water as there is nothing coming out of ANY of the taps.
I have a immersion heater (pumped cntrolled ysem)

thanks!