The answer to 'drain cleaning not working' is that there are several common causes, including a clogged drain, a damaged drain pipe, or a problem with the plumbing system. Symptoms may include slow draining water, foul odors, or water backing up in the sink or tub.
In many cases, a clogged drain can be cleared with a plunger, drain snake, or chemical drain cleaner. However, if the issue persists or the clog is deep in the pipes, it's best to call a professional plumber. They have the tools and expertise to thoroughly inspect the plumbing system, identify the root cause, and provide a long-term solution.