Old storage trunks lying in a basement or attic may contain family heirlooms or memorabilia, and opening them can seem impossible if the key has been lost. Often, the locks are quite simple and can be opened by a novice lock-pick using a couple of office supplies. Many of these locks can be manipulated with a little finesse, trial-and-error, and patience. The task is far easier if the lock isn't built into the trunk.
Cut the lock with a pair of bolt cutters. If the lock is not integrated into the actual trunk and is a pad lock or combination lock, simply cut it using bolt cutters rather than searching unproductively for a key or racking your brain for a forgotten combination. Wear eye protection, and cut with the snips pointed away from you.
Pick the lock. Use lock picks or bend a couple of paper clips. One paper clip should form an "L" shape, while the other should have a more subtle curve, resembling a dentist's tool.
Shine a flashlight into the lock's keyhole to see how the tumblers or pins are positioned. Slide both paper clips or lock picks into the keyhole. The "dentist's tool" should point toward the ceiling and the "L" clips should point to the floor.
Manipulate the deepest pin or tumbler upward with the "dentist's tool" until you hear it click, becoming disengaged from the lock. Once in an upward position, move the "L" clip under it to hold it in place. Repeat this process for the next pins or tumblers until all are being suspended by the "L" clip. The lock will open when every tumbler or pin is disengaged.