The lever on your bathtub operates the hidden stopper in the drain. If you have not used the lever in a while, you might find that it is stuck. This is usually due to the spring mechanism behind the faceplate. Repairing the stuck bathtub drain lever requires removing the entire mechanism from the tub. Often a simple cleaning resolves the issue. If necessary, replacement levers are available at home improvement centers and hardware stores.
Place a towel or rag over the bathtub drain to prevent dropping screws down the drain accidentally.
Remove the two screws securing the lever faceplate to the tub with a Phillips-head screwdriver. Grab the lever and slowly pull the faceplate away from the tub. The linkage for the stopper will come out of the overflow pipe. Continue pulling the lever and faceplate until the entire linkage and stopper are out of the overflow.
Straighten the end of the cotter pin securing the linkage to the back of the lever, using a pair of needle-nose pliers. Pull out the cotter pin and remove the linkage from the back of the lever.
Brush the spring on the back of the lever with a wire brush. This will remove the sediment and rust that is causing the lever not to move. Spray the spring with silicone and work the lever up and down.
Purchase a replacement lever if it will not move after cleaning. Sometimes the mechanism is just worn out or beyond a simple cleaning repair.
Line up the holes on the end of the linkage between the tab holes on the back of the lever bracket. Insert the cotter pin into the hole and bend the ends of the pin with the needle-nose pliers to secure the linkage.
Insert the stopper end of the linkage into the overflow drain. Push the linkage down the overflow with the lever faceplate until the faceplate is flush against the tub. Secure the faceplate with the retaining screws.