I have an Ideal Elan 2 boiler and the flame has gone out. Please help !!?

We have an old Ideal Elan 2 boiler and not had any problems with it so far (touch wood) but the heating didn't come on when it was supposed to, when i check it i found the pilot light has gone out and i don't know how to re-start it. I've read that you have to press a restart on on the side of the box which has the on/off knob and heating controls but i cant find it... Can any body help me please.....