Plunger drains operate using a lever. When you flip the lever, it closes or opens the drain. To clear this type of drain, first take off the cover plate. You will need to take out the small anchor screws that hold it in place. Gently, pull out the plunger assembly and any attachments.
Get a wire brush or toothbrush and some white vinegar. Soak your brush in the vinegar and thoroughly clean all the drain's parts. Using vaseline or heatproof grease, lubricate all pieces.
If the plunger drain is still clogged, you may have to open up your drain line.
Take off the overflow drain cover. Close the opening with a damp, balled-up rag. Take the stopper out of the drain and try plunging it with a small sized plunger. Plunge 15 to 20 times in an up-and-down motion. Repeat a few more times if the clog doesn't come out. If the clog still won't come out, move on to the snake method.
Find a small snake called a hand snake or auger, and use this to unclog the drain line. First, take off the cover plate from the overflow drain, and pull out the drain assembly. Push the snake into the opening. Keep pushing until you feel it hit the clog. Lock the snake line and turn the handle clockwish until you feel the clog break up. Put the assembly back in and replace the cover.