problem with worcester bosch 24i junior boiler?

Boiler is 3 years old and everything worked fine this morning, however, around 10.30am, no hot water. I checked the boiler and the reset light was flashing and there was no pressure in the system. I repressurised the system & bled the radiators and the manual vent pointand the boiler still will not ignite but goes to reset mode. Please help!