2007 GMC Envoy ignition switch

Someone has probably damaged the wafer-tumblers inside the Ignition Lock Cylinder, preventing the side-bar from dropping and allowing the cylinder to turn. It is surprising how easy it is to damage these tumblers by simply sticking the wrong key in the cylinder. You can request the procedure to remove the cylinder from me if you can somehow get it to turn, but you are best off calling a reputable locksmith.