If your drain is still blocked after using a plunger, there are a few steps you can take. First, try using a drain snake or a wet/dry vacuum to remove the blockage. If that doesn't work, consider using a natural drain cleaner like vinegar and baking soda. However, for persistent issues or if you're unsure, it's best to contact a licensed plumber for an inspection. They can diagnose the problem and recommend an appropriate solution.