Key won't turn in ignition

99 Sebring Convertable JXI. Yesterday I went to start it up and the key wouldn't turn in the ignition. This was the valet key. The master key did the same thing although it did turn once. I'm having the car towed to the shop today but just wondered if anyone else had seen this before.

The tow truck guy actually fixed this. He took a small hammer and struck the lock cylinder. Said the tumblers were out of whack. Anyway it hasn't gotten stuck since.

I agree, but now that it works, lubricate it with WD40.
This is a very common problem with the Chrysler vehicles these days. The lock is not reading the key so is will not allow it to turn.
Here is something that works more often than not. At this point you may need a new lock cylinder anyway so damaging the old one is not doing any more damage. With the ball end of a ball peen hammer, tap the chrome part of the lock cylinder (the face where the key goes in.) What you are trying to do is loosen the tumbler inside so they drop down and read the key. Sometimes they get stuck.
Only hit it as hard as you would if your thumb was in the way. We're not trying to dent it or break anything, just jar it. Then try the key once a gain.
If that does not work, then you can call a locksmith and if they have a mobile service, they can come out and replace the lock cylinder and key for @ $100.