If it's like the ones from way back in the 60's and 70's, push it all the way in, then push some more (carefully, but with enough pressure). It might click into position.
The old ones like that let you remove the button with the metal shaft attached by pulling it all the way out, then pressing a small button on the underside of the switch to release it. Reinstalling was a simple action. Insert it into the opening, then press a little more until it clicked into the fully-installed position.
The one in my 2005 has 2 buttons that you press to operate the lights: Parking (on the bottom) and Headlights (on the top), along with 2 sliders to control other stuff. When you press Headlights, it turns on the parking lamps by internally "pressing" the Parking button for you. Pressing only the Parking button turns on the parking lamps. When the lights turned are on at night by the light sensor, pressing the Parking button turns the headlights off, unless the Headlight switch itself is also pressed in. It's a convoluted way of controlling something so simple. I hate mine!
