Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
I hate to be the bearer of bad news, but if indeed you cannot remove the key from the ignition and cannot turn the key either way, then you're going to have no choice but to drill out and then replace the ignition lock cylinder.
If you are able to wiggle, jiggle, or in any other fasion, move the keyswitch backwards to the accessory position, then you will be able to remove the entire cylinder from the steering column and repace it.
If you can move the key backwards, then after doing so, if you look on the underside of the portion of the column where the lock cylinder is inserted, you will see a smal hole right about where your eyes imagine the tip of the key is.
While the switch is turned backwards insert a paper clip into the small hole and push in. At the same time, pull out on the key/cylinder and it should come right out. You might have to wiggle a little while you are pulling. Once the cylinder is out, you can reach in with a screwdriver and turn the actuator for the ignition (starter, etc.)
Let me know how it goes....