Feel the drawstring encasing until you find the cord. Hold the cord through the encasing between your thumb and forefinger, keeping your grip 1/2 inch from the end. With the opposite hand, push the encasing back toward the hidden end until you see the cord. Use the end of a pin to drag the cord from inside the shoe and retie it securely at the shoe's vamp.
Slip a small safety pin into the drawstring's opening if you are unable to retrieve the cord. Push the pin in just far enough to ensure that it fits into the encasing; then remove it.
Unstring the shoe completely and stick the point of the safety pin into an end of the cord. Close the pin and push it into the drawstring's encasing.
Slide the pin through the encasing, gripping the pin through the fabric and drawing the cord through the shoe. When the end of the cord is near the shoe's vamp, pin it to the drawstring encasing to prevent it from falling back inside the shoe. Continue until the pin surfaces at the other side of the vamp. Tie the cord at the opening.