Most filing cabinets have a small lock located at the top which is turned with a key. Cabinet locks are usually tumbler locks. Tumbler locks have a set of pins that are raised and lowered to engage the lock, using a set of keys. If you have lost the keys for the cabinet, you may need to drill the pins that engage the lock to open the cabinet.
Place the drill bit inside the drill. Press the drill bit into the top portion of the keyhole in the lock.
Press the trigger of the drill and begin drilling into the keyhole. Apply a bit of pressure on the back of the drill to get through the metal of the keyhole.
Press steadily as you get through the keyhole with the drill. You will feel a moment of no resistance before you reach the first set of pins. Continue pressing until you feel the drill give way with less pressure five times.
Reverse the drill and pull out the bit. Try opening the drawer. Clean out any of the metal shavings from the lock using a vacuum cleaner. Drill again using a larger bit to break the pins if the drawer does not move.