Well they actually make a sink plunger now, looks just like the toilet plunger but it's only about 1' long with a 4" rubber! Works really well, actually, if that don't work I use about a cup of Sulfuric acid, problem solved,

Use a good sink plunger and fill sink quarter way with water before plunging ! If it doesn't unclog the remove p -trap and snake from there..

Pour liquid detergent in the sink, wait ten minutes then pour boiling hot water into the sink now watch it flow.

C

C. block off the overflow opening in the sink so while you are using the plunger to unclog the sink wont come threw it.

The answer is c block off the over flow opening also run water, but if that do'sent work then drop the trap. If the trap is clean then you will need to us a sank run down the pipe.

C

I remove the drain stopper and flush hot water down the drain because three-fourth of the time it will be grease that caused the problem.

C

Throw it off the top balcony of a cruise ship while sailing the Mediterranean