Baxi Bermuda 552 model the radiators work but no hot water?

I have a Baxi Bermuda back boiler model 552 behind the gas heater last time it was serviced i must admit was 10 years ago but has never broken down except the pilot light going out on rare occasions and i could get it restarted but now despite everything seeming to work ie the pilot light is on the radiators warm up BUT the water stays freezing cold.
I had a chap from the National Grid come round to check for carbon monoxide or gas leak but the following day the hot would not heat up so don't know if this chap had anything to do with it but my main question is can i fix this myself?

Akhtar / Manchester
December 2009