The toilet is very old. It stopped filling with water.

After flushing water flows into the overflow pipe like normal, but it will not fill with water. There seems to be a sound like water dripping or flowing out somewhere. But the flapper feels tight. And if I fill the tank manually the water level stays.

Also, I lifted the float/arm up and it will not shut the water flow off.

It seems like there are 2 problems?

Thanks for any advice.

Replace the ballcock and your problem goes bye-bye. Good luck, Tom

Thanks speedball.

Upon further review the when I fill the tank manually 90% then turn on the water it fills up the rest of the way and the ballcock pops up and the water shuts off.

But after flushing the same thing happens where the water turn on, the flapper valve is tight and the bowl fills but the tank will not.

Still a ballcock issue?

If it's more than 5 years old replace it. The fancy fluidmasters with even the leak detect feature which I think I like are only about $13.
Yea, you could have problems removing the toilet supply line, but there solveable.

Some of the newer ball cock valves, you can remove the top, with the water supply off, of course and flush the debris out by turning on the valve BRIEFLY under an inverted cup.

Bet, your ball cock if you manually raise it slowly it spits and sputters. I think you established that water is not comng into the tank with it fully down?

Yes, that is right. With the ball cock down, the water is not coming into the tank. Have not tried raising the ball cock slowly. But if there is hardly any water in the tank, like after I flush, and I raise the ballcock the water does not stop. Only if there is water in the tank, that I put in manually, does the water stop if I raise the ballcock.

Replace the ballcock! Your old ballcock gave up the ghost. Put it to rest with a nice headstone. Good luck, Tom