The answer to 'why is my pipe won't flush' is that a clogged pipe is the most common cause. A clog can form from buildup of hair, soap scum, food particles, or other debris in the pipe, preventing proper flushing. Symptoms include slow draining, gurgling noises, or complete blockage.
If the clog is minor, you may be able to clear it yourself using a plunger, drain snake, or chemical drain cleaner. However, if the clog is severe or recurring, it's best to call a professional plumber. They have specialized tools and expertise to fully clear the blockage and address any underlying issues in the pipe.