Why would the pilot have gone out anyway in the first place? i am not sure?
Over time dust and dirt accumulates in and around the pilot injector,this restricts the amount of gas being passed and thus reduces the size of the pilot flame.With the pilot flame reduced it cannot heat the thermocouple,no heat to the thermocouple shuts down the gas valve.
You cannot relight the pilot because the pilot is to small and/or it isn`t heating the thermocouple.
Get someone in( an RGI) to service the boiler,it sounds like it hasn`t been done for a while.