If vinegar didn't work, try a mix of 1/2 cup baking soda and 1/2 cup salt. Pour it down the drain and let it sit for several hours (or overnight). Follow with boiling water. The salt acts as a more abrasive scrubbing agent.
Baking soda, also known as sodium bicarbonate, is a natural mineral compound that is commonly used in baking and cleaning. When it comes to unclogging blocked drains, baking soda works in two ways:
If all else fails, place a bucket under your sink and unscrew the P-trap (the U-shaped pipe). This is where hair and gunk often collect. Clean it out manually and screw it back on. This solves the vast majority of stubborn sink clogs.
