If you forget the combination to a Master Lock that has an imprinted serial number on it, you may be able to recover the combination from the company. Master Lock does not provide combinations for locks without serial numbers. Company policy prohibits the release of a combination to any lock attached to another object, as of 2015. If you cannot recover the combination, cut the lock and purchase a replacement.
For security reasons, Master Lock no longer imprints serial numbers on its locks. However, if a lock has a serial number and meets the company's other criteria, owners should take it to a retailer. The retailer then calls the manufacturer to verify the owner's identity. The second option is downloading the lost combination form from the Master Lock website and completing it. Have the form notarized and send it by mail to Master Lock. The company then provides the combination.
If you are unable to obtain the combination from the manufacturer and the lock is preventing access to your property, obtain a pair of bolt cutters rated for 1/2-inch bolts. Slide the cutting head over the shaft of the lock opposite the side where it opens and cut the shackle by squeezing the handles together. This process ruins the lock, so have a replacement ready to secure the contents again.