Take the button off, should just pull off. Then you need to take the snap ring off from the inside of the shifter knob. Use snap ring pliers (easiest) or a couple of picks (not as easy) and the knob will pull off.

Look at the transmission driver's side and see if the cable came off. I've seen that before. Might be easier fix than pulling the shifter apart. The cable could have came off at the shift point on the transmission or at the bracket. Both are on the driver's side.