Many ovens have a switch that turns the interior light on and off when the door is opened. The switch is located on the door jamb, and when pushed in by the oven door, turns off the oven light. When the door opens, the switch decompresses and the oven light turns on. In case your oven light switch has broken or malfunctioned, it needs to be replaced. Always disconnect the power to your oven prior to servicing the appliance.