You may never run into this problem, but I have met a few who have. I've even helped a few people get their van going again who were having this issue.
When I first got my Caravan, a problem developed where I couldn't turn the ignition key.
For about a week, I thought I was in trouble and was going to have to do an ignition lock change.
Occasionally, I could insert the key into the lock, but it wouldn't turn. This was a SERIOUS problem for me as I found myself stranded a few times until I was able to eventually "muscle" the key to turn (but also by figuring out the dynamics of the problem).
For anyone who runs into this issue, I never changed the lock or switch and no longer experience this problem.
An immediate fix is to tap on the metal ignition lock (right where the key goes in) firmly with a solid object that fits the diameter (or less) of the ignition lock. Usually, this will free the lock until you park crooked again. The head of a screwdriver is usually all it takes.
The permanent resolution was an adjustment in how I parked the van.
I learned that no matter where I parked, all I had to do was keep the front wheels dead straight ahead by centering the steering wheel before I turned the key off and this problem has COMPLETELY gone away. I no longer even realize I do it. It is habit and I never really notice I'm doing it anymore so it's no bother at all. I suppose I could replace the ignition lock, but I am satisfied with the method mentioned.