Use a flashlight to look down into the lock through the spaces around the thumb wheels. Carefully turn each wheel until you see a small notch in the disk behind the thumb wheel. Line up all 3 wheels so the notches are facing up (toward you) as you look down at the wheels. Turn the lock over so you can see the number on each wheel. From there, add 1 digit to each number, and repeat this 8 times until you have a list of 10 3-digit codes. Try each of these codes until you find the right combination. Once you successfully open the lock, you can reset your combination.