Gear shifter inside of car on GS model

[ljwoman1956]

I have a 1997 Regal GS that I had to remove the top of the gear shifter (the part that has the button you push down in order to put car into gear) because my car would not go out of park into drive. It would not go into drive or anything. My son removed the cover with the button was was then able to put car into drive. What is the problem so that I can look up a solution to this problem. I don't know the correct terminology