how to unclog toilet when plunger does not help
You can buy an inexpensive snake, at a hardware store. It is easy to use and unclogs what a plunger can’t.
You can buy a toilet auger. If that doesn't work the clog is further down the line and will need to be rodded. Then you need a plumber.
You can try pouring about a cup of dish soap into the toilet then add super hot water. Let sit for a few minutes, then flush. If that doesn't work, you'll need to "snake" it out.