how can i fix my 96 megane?

my p reg megane just stopped working .when i try to start it ,it just ticks over i changed carb because i thought the fuel was not getting though it ,but just the same with new carb,my mechanic friend thinks it is to do with my immobiliser,but im dumbfounded with that as i have never known there was one ,i do have a flashing red eye in my car but never in 12 months have i needed to do anything to start my car .if this is the problem how do i get my immobiliser number