As said it's not your switch as you said the headlights work and headlights are switched via ignition. When you turn ignition on do you hear pump prime and warning lights illuminate? When you turn to starter position do you hear the solonoid click or is there just nothing at all? If nothing you need to check power to starter. Get underneath and check the big heavy feed to the starter this should read battery voltage followed by checking power to starter solonoid with someone turning key to starter position why you do so, again should see power.

Also should mention the starter may be jammed as I noticed you said the light dull slightly which would indicate power is getting to starter. Try putting car in top gear and rocking back and forth see if it frees it, although can't see how it would jam when it's not engaged mid drive.

Martin.