Why did it go out? Was there a fault? Has it been fixed?
Assuming there's no inherent fault . . .
I don't know this boiler, but there will almost certainly be a spring-loaded button which you have to hold in to over-ride the flame protection unit, and allow gas to flow to the pilot. Then there will be a smaller button which you have to press to generate a spark to light the pilot. Once the pilot is alight, you need to hold the first button in for another 30 seconds or so to allow time for the thermocouple to heat up. Then you can let go of the button, and the pilot should hopefully stay on.
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