Ignition diagram for 2000 Pontiac grand prix ft

SOURCE: diagram on a pontiac grand prix

I have 07 Pontiac Grand Prix, the wrong key was inserted into the ignition the other day. Now when I try to use the correct key it will not insert completly in the ignition, goes in until last 1/4in of key. Im stuck, I bought the new lock cylinder but how do I get the old one out? I cant get the key to insert all the way so I cant get it to the "On" position, it will not turn at all. The key that was inserted in error is whole and nothing is missing it seems like there is something stuck. Any help would be appreciated...