A stuck shower handle can put a damper on your personal hygiene schedule. When the faucet is stuck, you will be unable to turn the shower on at all, rendering it useless. Shower handles get stuck for various reasons, including rust and water scaling. If your faucet handles are stuck for any reason, troubleshoot the problem and fix them.
Turn off the water to the shower at the shutoff valve. This will prevent you from getting soaked when the handle is finally fixed.
Lubricate the handle with industrial lubricant, transmission fluid, or hydrogen peroxide and allow the liquid to saturate the metal. Gently twist the handle until it begins to turn. Try the lubricant first. If that doesn't work, move onto the other two products.
Plug a hair dryer into one of the outlets in the bathroom. Point the hair dryer at the area where the handle attaches to the wall. Turn the hair dryer on and move it around the handle, evenly heating the entire surface. Do this for five minutes and then turn the hair dryer off. Twist the handle gently to get it to turn. The heat will help any corrosion break up and will help the metal expand and be able to move a bit better.
Strike the faucet handle gently with a hammer. Use light, even strokes and hit the area where the faucet meets the wall. Be careful not to go too fast or hard as this can damage the pipes and the handle. The goal here is to simply get it to move again.
Several lubricants are designed to work on faucet handles, but if the generic lubricant is cheaper, try it. It should work almost as well as the designer lubricants.
Use only enough force to loosen the handle. You don't want to damage the rest of the plumbing with your fixes.