The answer to 'why is my pipe won't flush' is that there is likely a blockage or clog preventing proper water flow and drainage. Common causes include debris buildup, mineral deposits, or a physical obstruction in the pipe. This can result in slow or incomplete flushing, gurgling sounds, or even a complete inability to flush the toilet.
To troubleshoot the issue, you can try plunging the toilet or using a drain snake or auger to clear the blockage. If that doesn't work, the problem may be deeper in the plumbing system and you may need to call a professional plumber to inspect and clear the pipes.