If you've lost or forgotten the combination to your briefcase or suitcase and need to unlock it, there are a few methods that work. The make and model of the lock might alter your success rate, so if one method doesn't work, try another before making the decision to break the lock or go to a locksmith.
Number Tension Method
Sit the briefcase on its side with the latch and code dials facing you. Slide the latch toward the open position. The case won't open because it's locked, but hold the latch open as far as it goes. Roll each number dial, paying close attention to which dial is most difficult to roll. Set this dial to "0." Begin to roll the other two dials, checking for tension. If they roll freely, you need to move the first dial to "1" and check the other two for tension again. Repeat this until either of the dials becomes tight when you're rolling. That's the first correct number. Set the second dial to "0" and rotate the third dial. Increase the second dial's number until the third dial is tense when rolling. That is the second number. Once you have the first two numbers, rotate the third dial until the latch pops open.
Unbend a paper completely, and flatten one end with a hammer. With the briefcase dials facing you, extend the end of the clip through the right side of the dial. Roll the dial numbers; on each number run the paperclip from top to bottom. The correct number is designated by a spacing or gap that you feel with the paperclip. Do this for each dial, leaving each one set at the correct number. When you find the last number, the latch should pop open when clicked.
Unlock By Sight
This may seem like an impossible task, but you can unlock the combination by sight with a flashlight and magnifying glass. Shining the flashlight into the right side of the first dial, look through the magnifying glass. You should see a flat edge. As you rotate the numbers, the edges will remain smooth and flat until you reach the correct number, which has a bumpy edge. Leave the number set and move on to the next dial, repeating until you have the second and third numbers. Check the latch, making sure it opens, and note the combination.
If this hack doesn't open the lock the first time, the combination number might be on the mirror side of the number showing on the dial. This means you will either add or subtract five from the number shown. For example, if you see "394" on the dial, add five to any digit valued less than five, and subtract it from any digit over five. Thus, add five to "3" making it "8"; subtract five from "9" making it "4";d add five to "4" making it "9." The resulting inverted code becomes ""849."
If all hack attempts don't work, take the briefcase to a locksmith for professional help.