How to Unclog a Toilet with a Plunger
Repeat Step 4, but this time, pull up sharply, releasing the suction.
Hopefully, when you release the suction on the drain the clog should be dislodged releasing the water. If there’s no change, repeat Steps 4 and 5 until the water begins to drain.
If you've tried these steps a couple of times with no progress, it's time to pull out the plumber's snake.