You should be able to use the key that is used to start the car. Place the key inside the key slot that is in the front of the glove box and turn counter-clock-wise, this should unlock it!
Remove the two screws from the dash side that are holding the hinge underneath the glove box. They made the glove box all one piece so the whole unit must come out for it to be serviced.
I just replaced mine and we had to go from underneath it. Once you disconnect all the bolts and wires you still have to remove the brackets around it so it will fit out.