A sink's drain plug will become stuck if a clog forms high in the drain, near the opening, or if the plug's mechanism comes out of adjustment, altering how the plug will move. Before you can use the sink fully, you must repair the plug. Correcting the problem takes less than 20 minutes to complete.
It's necessary to examine the sink's plug mechanism and the drain itself before you begin working so you can confirm why the plug is stuck. Raise the plug to an open position, if possible, and shine a flashlight into the gap between the plug and the sink's drain opening. If you can see slimy or hairy build-up on the underside of the plug or in the drain itself, the build-up could be the cause. A loose or broken part on the plug's mechanism under the sink can also cause the plug to stay put even though you are moving the lift rod up and down.
Before you can check for clogs in the sink or examine the plug to see if it is broken, you must remove the plug from drain. Some plugs simply pull straight up and out of the drain opening. With other plugs, it's necessary to unscrew the plastic nut on the side of the sink's drainpipe and pull out the pivot rod from the drainpipe before you can pull the plug out of the drain.
Check for Clogs
Once you have removed the plug from the sink, you can shine a flashlight down the drain's opening to see if a clog sits near the drain's opening. If you can see the clog, reach down the drain and pull it out with needle-nose pliers, a wire hanger or your fingers. The flashlight will help you also look down the drain periodically so you can see if the clog is completely gone. The clog itself will probably smell, so put it into an outside garbage container if possible.
Readjust the Mechanism
A stuck drainplug may also be caused by the plug's mechanism coming out of adjustment. With the whole mechanism put together, close the plug by pulling up on the lift rod. Locate the screw on the clevis strap, the piece that connects to the lift rod on the underside of the sink. Loosening the screw with a screwdriver will allow the whole mechanism to readjust itself, so do not touch anything other than the screw. Once the mechanism has sat with the screw loose for a minute or so, tighten the screw again. Check your work by filling the sink with water to see if any water escapes past the plug.