Betty- After the toilet fills up, turn off the water to it. Check back in a couple of hours and see if the water level in the tank had dropped. If so, the new flapper is not working. Make sure the flush valve ( the thing the flapper seals against} is clean (use SOS pad}. Make sure the chain has slack, and that you have the right flapper. Otherwise, replace the flush valve . If it is ceramic , molded into the tank, you cant.
