The problem is related to the cable that goes between the ign cyl and shifter. It's usually something as simple as the shift lock release button stuck downwards because soda spilled on it. If so, you should be able to get it to pop up again with a little penetrating oil, silicon spray and maybe a small screwdriver. That button causes the cable to not allow the key to be removed.
If you're not that lucky, you'll need to remove the center console and see why else the cable or button is sticking.