How do you get the hot water back on?

I have a glow worm space saver 38, which tried to give up the ghost the other night by leaking an awful lot. My friend came round (not a plumber) and he turned everything off, and drained the water out (a lovely dirty brown shade it was, mmm). The next day a plumber fitted a new pump, as this was apparently the original problem. Now the heating is fixed, and it leaks no more, but there is absolutely no hot water, and it doesn't even seem to be filling the tank up. I have no clue what to do, and I have no money for a new boiler, also I have 2 small boys, and they need baths without having to wait an hour for me to boil the kettle and pans! I am at the end of my tether and all I want to do is rip the blasted thing off the wall and give it a kicking!