Your toilet seat raises and lowers on a pair of hinges. These hinges are located at the rear of the seat and connect the seat to the base of the toilet. Hinges can become broken or worn over time, and need to be replaced. This will be a more economical option than purchasing an entire seat-and-hinge replacement set, especially if your current seat is perfectly functional.
Lift the toilet lid and locate the two hinges at the base of the seat. Remove any screws securing the hinges to the toilet lid. Set the toilet lid aside.
Pry open the two protective caps on the toilet-base portion of the hinges. You may need a wide flathead screwdriver for this operation.
Remove the plastic bolts beneath the protective caps. Each bolt will be held in place by a nut. The nut can be found on the underside of the toilet. Hold this nut with your fingers while unscrewing the bolt. Remove the hinges.
Purchase replacement hinges. Be sure that these replacements are compatible with your old toilet lid. Take the old hinges with you to the hardware store.
Attach the new hinges to the seat first. Tighten the screws.
Unsnap the protective caps from the other end of each hinge. Align each hinge with the bolt holes on the toilet base.
Insert a bolt and washer into one of the bolt holes. Screw the accompanying nut onto the bolt. The end of the bolt will be located on the underside of the toilet. Holding the nut in place with your finger, tighten the bolt head with a screwdriver.
Close the plastic cap onto the hinge. Repeat steps 4 and 5 for the second hinge.