It sounds like you need to refill your system from the cold inlet valve as the pressure has dropped, turning off the pilot for safety.
If you can identify it from your handbook you just need to fill it to the recomended pressure (bar) and your boiler will more than likely spark back up. Often it is a blue turn knob or can be a screwdriver type slot - but you need to identify it on your boiler first. On mine it is the blue turn knob. All I need to do is turn it so you can hear cold water rushing into the system and watch the pressure meter increase. Depending on your boiler - fill it to at least 1.5bar, stop filling and try and turn your hot water on. It should then flare up.