You will need two paper clips to unlock your filing cabinet without the key. Unfold the paper clips so there is a hook at the end of each. Take one and insert it at the top of the lock. There should be four pins. You will want to start at the top of the lock. Apply pressure sideways to make the pin move and lock into position. Move down and do the same with the other 3 pins. Once the pins are in place, insert one paper clip at the top and one at the bottom of the lock. Then turn to unlock.