How can I fix my friendly Sime format 80E?

My boiler tries to light up and keeps on making clicks to light up. Fan is working , lights are on but not pilot light at front panel. Normally when working pilot light at front is green. It changed to red for one day and now no light. When you start it you can hear pump starting but it does not fires up. So it keeps on clicking to start. All the rest seems ok.