How to Unclog a sink?
There's probably plenty of gunk just below the bowl stopper. That's easy to remove and clean. You can also remove the J trap under the sink and clean that out.
Take a wire hanger, straighten it out and jam it down in there, it works better than Draino! :-)
Run a pipe cleaner through it. I'm referring to the long sticks with hooks or fuzzy stuff around them, like the Draino dual action kit.
You can use a plunger, a commercial drain clog dissolver like Drano, you can use a pipe "snake", remove the bend in the drain pipe and manually remove the clog. Call a plumber.
Yeah like everyone said, you can just grab an ordinary toilet plunger and try to unclog youre sink.
baking soda & vinegar
It's most likely hair. Home depot has something that looks like a ruler with sharp razor teeth, inexpensive, disposable.