biasi combi boiler?

please help its a biasi combi model number m96 28 Smc, HAD it on the frost symbol last 2 nights over night, come switch it on today and the "lock out"lamp was on, i pressed reset button and it fired up for few mins, then flame went out and "lock out" lamp came back on, thats all it keeps doing... and im a female alone and gas and boilers are very alien to me.. thankyou