Determine if the ligature is simply bent or if it is broken. If it is broken, you will need to buy a new one.
Carefully pull the ligature apart until the opening has a round shape and can slide over the top of the nozzle.
Slide the ligature into the mouthpiece slowly but firmly. As the ligature slides into the mouthpiece, it begins to take shape. Unscrew the screws slightly to pull it down completely.
Squeeze your hand around the ligature once you have pulled it to the place where it usually sits. Squeeze it slightly to retain its original shape.
Slip the ligature from the nozzle. Forge some kinks with your fingers.
Replace the ligature on the nozzle and make a turn. Play your clarinet to make sure it holds your tear in place.
Tips and warnings
A clarinet ligature is small and light, which makes it easy to release when you put it on or take it off a mouthpiece. If your foot or knee finds it before your hands and you bend it, it is relatively easy to mold back into shape.