If the ignition switch is on the front panel near the gas control knobs, then it is possible that it has got 'gunged up' (technical term !). You should be able to release this from the panel with careful use of a small screwdriver blade.
Then pull off the leads and carefully 'short ' them with a piece of insulated wire stripped at each end. If the igniter clicks and works, then all you need to do is replace the switch - If not then the fault is elsewhere and more will have to come out. Oh, and check the 12v fuses first as previously advised.
Over the years I've had two switch failures of this sort, plus one which was a loose connection at the back of the switch.