Depending upon the weight and force used when sitting on a toilet seat, the mounting bolts can break off. To preserve the safety of your own delicate seat, you will need to replace a broken toilet seat bolt to prevent pinched cheeks and other unfortunate accidents. Follow these steps to fix broken toilet seat bolts.
Lift the hinge cover, using a knife or your fingernail.
Use pliers to loosen the plastic nut on the bottom side of the bolt. If the broken bolt is rusted, spray some WD-40 around the nut to help loosen it. Once the nut is loosened, unscrew it to remove it completely from the bolt.
Push bolt up through the hole and remove it from the toilet seat. Clean and dry the area beneath the mounting hinge thoroughly before replacing the bolt.
Insert new bolt from top. On the bottom side, slip on the washer (if applicable) up to the base of the toilet and then screw on the nut.
Snap bolt covers back into place.
If you have difficulty remembering which direction loosens and tightens a screw, think about this: righty-tighty, lefty-loosey. If the bolts are so rusted that you cannot remove the nuts, you will have to use a hacksaw to saw through them. Make sure you have the right length of bolt (typically 2 1/2-3 inches long). If the bolt is too short, the nut will not fit properly and the seat will again come loose.
Do not overtighten the nut as this will weaken the bolt and cause it to break.