Shut the water supply off to the toilet. Flush the toilet. Pull the old flapper out and replace it with the same type. Turn the water back on and test the toilet.
Wrong adjustment
Mine has neither and it works perfectly I install this type all the time
A toilet flapper is found inside the tank of a toilet. It is a rubber stopper that rests over the water outlet. As the bowl is flushed, the apparatus lifts the flapper over the drain outlet hole. As the bowl and tank refills, the apparatus drops the flapper so it is again seated over the drain hole. Once the water in the tank reaches a certain level, the water automatically stops. Note: If your toilet constantly runs, most likely the flapper has not completely seated itself in the hole. Hard water can cause mineral deposits around the drain which prevents the flapper from seating properly. Also the rubber can become old and leak around the edges.NOTE: Not to be confused with 1920s "flappers", women who dressed in short skirts, gaudy jewelry and headbands, and were fond of dancing.
There are main five reasons for your toilet does not flush. Clogged in the toilet Poor/defective pipe Quality tank water level is low. Damaged flapper Inlet holes blocking These are the most common problems, you can check these one by one and solve your solutions.
Shut the water supply off to the toilet. Flush the toilet. Pull the old flapper out and replace it with the same type. Turn the water back on and test the toilet.
I think the flapper is not closing properly. Try adjusting the flapper or replacing the flapper with a new one.
Wrong adjustment
remove and install a new filler valve and get a proper flapper for your toilet at a plumbing supply
the flapper in tank is not sealing after flush.change flapper.
Replace /bulb / flapper /disc and check the over flow tubeA:The kits are inexpensive and come with the float and the flapper assembly.
My behind
Where is it leaking ? Flapper in the tank, replace flapper. Between tank and bowl, separate and replace the seal. Toilet to floor. Replace the wax ring under the toilet, making sure it is thick enough to form a seal and the bolts are installed correctly and holding the toilet down.
because there is a Dukie stuck in the bottom of the toilet so you have to take out your toilet and flush the system.
Check the flapper and re-adjust the fill height.
Flapper in tank sticking or not seating properly. Needs replaced.
New flush valve may be needed.