Having a clogged sink is never fun. There are cleaners you can buy from the store, but that's really not necessary. Save some money and use a vinegar solution instead, which usually works just as well. Pour around a cup of baking soda down your drain and let it sit there for a couple of minutes. Next, pour a cup of vinegar down the drain. You'll see the solution start to fizz.
The strong chemical reaction is almost guaranteed to unclog any dirty drain. After the reaction has stopped, run your tap on full pressure to wash everything away and make sure there's nothing still stuck in the drain.