The answer to 'sink not working' is that there could be several common causes, including a clogged drain, a broken garbage disposal, or a leak in the plumbing. Symptoms may include water not draining properly, foul odors, or water leaking under the sink.
Some potential solutions include using a plunger or drain snake to clear a clog, replacing a faulty garbage disposal, or tightening or replacing worn washers and gaskets to fix a leak. However, it's important to determine the root cause before attempting any repairs, as more complex issues may require the expertise of a professional plumber.