Remove any screw keeping the rollers in place with a screwdriver. Turn the screw counterclockwise as far as you can to release the rollers from the door. Pull the rollers from the door to identify their type. Rollers vary in shape, size and brand. You can take the rollers to a hardware store to find a perfect match. Screw the new rollers into the bottom of the door. The side with the holes or countersink screws should line up with the holes on the door. Insert the screws and turn them clockwise until they are tight. Make sure the wheels are facing down towards the bottom of the door.