Remove any visible debris from the drain opening
Boil water and pour it slowly down the drain
Add baking soda to the drain
Pour vinegar into the drain
Let the mixture sit for several minutes
Flush the drain with hot water
Use a plunger over the sink drain
Seal the overflow opening if present
Repeat plunging several times
Remove and clean the sink trap under the drain
Place a bucket under the trap before removing it
Clear any buildup from the trap
Reassemble the trap securely
Use a drain snake or auger to break up the clog
Insert the snake into the drain and rotate it
Pull out any debris attached to the snake
Run water to check drainage
Use a wet-dry vacuum if available
Call a plumber if the clog remains