Squirt a few tablespoons of dish soap down the drain, then pour hot (not boiling) water. Soap helps lubricate and break down greasy clogs.
If nothing works after a few tries, the blockage may be deep in the pipes. Avoid chemical drain cleaners—they can damage pipes and harm your skin. Call a plumber for persistent clogs.
Straighten a wire coat hanger and bend a tiny hook at one end. Gently fish for hair and gunk around the drain opening. Pull out debris carefully—wear gloves.