Turn off the electricity to the recessed light at the main breaker box to the home. Although you will not access any of the electrical components of the light, you will use metal tools and can receive a shock if the power is still on.
Place a ladder underneath the recessed light and climb up onto it so that you can easily access the light. Reach into the center of the light and grasp the light bulb. Turn the light bulb counterclockwise until it detaches. Set the light bulb in a safe location.
Examine the outer edge of the recessed light where it meets the ceiling for a thin, circular piece of metal called the trim. Insert a slotted screwdriver under the trim where it meets the ceiling and pull it off. In some recessed lights, the trim is not removable.
Insert your hand up into the fixture hole and grasp the cone-shaped baffle. Pull the baffle down by 2 to 3 inches until you can insert your other hand above it in the light box. Locate the spring attached to the baffle and detach it from the mounting hole in the light box. Lower the old baffle down out of the recessed light.
Pick up the replacement baffle and turn it so the smaller end faces upward. Grasp the spring at the top with one hand and raise it up to the inside of the light, insert the end of the spring though the hole that the old spring attached to. Remove your upper hand and allow the baffle to spring upward into position.
Insert the round metal trim back over the perimeter of the recessed light, if applicable, and press it until you hear a click.
Reinstall the light bulb and then turn the power back on at the main breaker box to test that the recessed light still functions properly.