A very common bathroom plumbing problem is having a toilet that won’t flush properly or won’t flush at all. If the toilet doesn't flush at all, now matter how hard you pull the handle, then there could be a couple of things wrong with it, depending on the type and brand of toilet you have.
Concentric-float fill valve
The most common flushing mechanism used by professional plumbers nowadays is the more modern flush valve assembly that is all plastic with only a few moving parts and only one little circular rubber part controlling the flow of water to the tank, called a “Tank fill valve”. The newer concentric-float fill valve consists of a tower which is encircled by a plastic float assembly. Operation is otherwise the same as a side-float fill valve, even though the float position is somewhat different.