Insert an appropriately sized steel drill bit into the chuck of an electric drill and tighten securely with a chuck key. Choose a drill bit that fits the longest part of the keyhole entry point. This permits the bit to focus on the destruction of the lock tumblers.
Apply a small amount of machine oil to the drill bit to reduce heat caused by friction generated by drilling the metal lock assembly.
Begin drilling at a medium speed applying a firm, steady pressure on the drill. When the drill completely penetrates the lock mechanism, set the drill into its reverse mode and slowly extract it from the file cabinet lock.
Insert a flat-head screwdriver into the slot of the lock mechanism and turn clockwise. If the file cabinet lock is completely destroyed internally, the release lever will trip, allowing access to the cabinet drawers.
Repeat Steps 1 through 4, graduating to the next largest drill size if needed.