Can't turn the key on 2001 Jeep Grand Cherokee

Just today, I tried to start my Jeep but could not turn the key. Not at all. Steering wheel not locked, tried that already. Any thoughts?

2 answers
Sounds like the lock cylinder has failed, But if you have a spare set of keys try that first
I have this problem often and just need to play with the key. Wiggle it around and move the steering wheel. I will engage eventually.