This problem seems to be often happening. There is a way to open the box without destroying it. You should drill a small hole (2mm) in the door, at the location where the catch is on the inside. If you than take a long thin pin and juggle around it will open.
If you want I can go look for a digital camera to take a photo for the exact location of the hole and email it to you.

Normally this problem is caused by a small pin inside the lid that is supposed to move the catch. Of you use the key to lock than this pin will not be able to move the catch. Sometime this pin breaks and this has the same effect as being locked. After opening the glove box you should open the inside of the lid and locate where the pin has been. You can take out this part, drill a small hole were the pin used to be and put in a small screw. Problem fixed.