The answer to 'sewer line won't flush' is that there are several common causes, including a blocked or clogged sewer line, a broken or collapsed pipe, tree root intrusion, or a problem with the septic system. Symptoms may include slow draining sinks and tubs, gurgling noises, or sewage backing up into the home.
For minor clogs, you can try using a plunger or a drain snake to clear the blockage. However, if the problem persists or you suspect a more serious issue, it's best to call a professional plumber. They can diagnose the problem, use specialized equipment to clear the line, and make any necessary repairs to the sewer system.