Ignition switch

Try lightly tapping in the key opening with a hammer then see if it will turn?Also does the key look with down or damaged? This guide can help plus I have added how to replace the ignition key tumble in the diagrams below.

https://www.2carpros.com/articles/ignition-switch-wont-turn-stuck

Check out the diagrams (Below). Please let us know what you find.

There are 4 things that I see over and over again, that keep an ignition lock cylinder from turning.

1.
The steering wheel lock is under pressure.

When you turn off your car and remove your key.
A spring loaded post sticks up in to one of many holes in the steering wheel.
This locks the steering wheel in place, making your car harder to steal, because a bad guy cant turn the steering wheel if they somehow get your car started without the key.

But this can also keep you from turning the ignition lock.
If the steering wheel is under pressure because your front wheels are against a curb, or you have the wheel cranked all the way to one side or the other. The pressure from the steering wheel on the spring loaded post keeps you from being able to turn the key.

So while trying to pull the steering wheel one direction or the other, try to turn the key, this may solve your problem.

2-A.
The pins are not falling into place.

You kinda need to know how a lock works for this part.
Look at a key and you will see there are different depth cuts in it.
Those different cuts correspond with different length pins in the lock cylinder.
See how the red pins are of different length?
But with the key inserted, they are all even with the blue pins.

When the red pins are held in the correct position by the correct key, the spring loaded blue pins are flush with the outer housing of the lock, and the red pins are flush with the inner cylinder of the lock
And thus the inner cylinder can be rotated.

If debris such as pocket lint, ear wax, or just plain old dirt gets into the pins and causes enough friction for the spring loaded blue pins to not be able to push the red pins back in place.
Then the red pins will be partially stuck in the hole for the blue pins and the cylinder can not turn.

Putting the key in the lock and then tapping on it with a small hammer may help until you have the chance to have the lock cleaned.

Do a search for the word "bump key" if you want to know more about how a lock cylinder works.

2-B.
The same goes for if a key is worn out.
If a key is badly worn, then it will not put the red pins in the correct spot and some of the pins will keep the cylinder from turning.

If your key is worn out, try a spare if you have one.
Or put the key in and "Jiggle" it while trying to turn the lock.

3.
A problem with the interlock cable from the gear selector to the lock cylinder. Make sure you are completely in park.
You pretty much have to take things apart and visually inspect it to verify this problem.

4.
A mechanical problem with the linkage from the lock cylinder to the electrical part of the ignition switch.

good luck

Ensure turn signal lever is in center of OFF position. Disconnect negative battery cable. Disable air bag system.
Remove steering wheel. .
Remove bolt/screws from lower steering column cover. To disengage locking tabs, tilt cover down and slide back. Remove lower steering column cover. Remove bolts/screws and upper steering column cover.
Remove wiring harness straps necessary to disengage steering column wiring harness. Disconnect steering column electrical connector from vehicle wiring harness. Disconnect Brake Transmission Shift Interlock (BTSI) electrical connector (if equipped). Disconnect Gray and Black turn signal and multifunction switch connectors from steering column electrical connector.

Remove bolts/screws, and remove turn signal and multifunction switch from vehicle.

Using small screwdriver, gently pry retaining clip on key alarm. Rotate alarm switch 1/4 turn, and remove alarm switch. Remove 2 switch mounting screws.

Remove wiring harness from slot in steering column tilt head assembly. Remove ignition and key alarm switch assembly.

Easiest is to go right to the starter relay under the hood. Remove it and test all for terminals in the socket with a voltmeter or test light. One terminal will have 12 volts all the time. A second one will have 12 volts only with the ignition switch in the "crank" position.

For the remaining two terminals, move the ground lead of your meter or light the battery positive post. Now you're testing for a good ground circuit. Probe the last two terminals. One will show continuity to ground all the time through the starter solenoid and motor. The last one will also show continuity but it will go open circuit when you shift into "reverse" or "drive". That's the neutral safety switch circuit.

In some GM circuits the neutral safety switch is in series with the ignition switch. If that's how your car is wired, the two ground terminals will show continuity to ground all the time, and the switched 12 volts from the ignition switch will go away when not in "park" or neutral". Those four tests will tell you which part of the circuit has the problem.

You will to get a lock depressor auto stores will loan you one.
Disconnect batterry remove horn pad
you will see nut that holds steering wheel on
remove nut you will see a mark where the steering wheel lines up if not there mark with paint for realignment.

Should be able to pull steering wheel off by hand it will be hard but hitting the back of it with your hand will help.

After you have the wheel off you will see the lock plate attach your lock depressortighten down to depress lock when lock is depressed you will see a lock ring remove this with a sharp object

release pressure on lock plate remove lock plate and spring now you are looking at white plastic turn switch remove the three screws now the switch will lift up on pass side after you remove the flasher knob.

Now you are looking at a torx screw remove this screw remove lock cylinder install new