Key won't turn - Help

I have a 2002 Grand Caravan and the key WILL NOT turn :screwy:

I put the key into the ignition and try to turn it and it's locked.
I've tried stepping on the breaks, make sure it's in park (although I can't make sure as I can't turn the key to get the lights on)...

Any idea what this could be? It seems very strange, as it was working perfectly then my little son was playing with the key and put it in the ignition, when I told him to take it out he did...nothing seemed out of the ordinary. I tried them to start the Van to go out and was unabled...

Any help, ideas are greatly appreciated.

Thanks,

Sounds like the key lock cylinder tumblers are shot (seems to be common to our cars, in the last year i have replaced this item on a '96 Caravan and '98 Neon). If you are planning to replace yourself, you will need to take the trim covers off around the steering column, then put key in ignition and try to turn it as it must get to the on (not start) position (I had to take a rubber mallet and tap the lock cylinder while trying to turn the key to get the cylinder to move). once the ky is in the on position, look at the bottom side of the cylinder housing and you will see a flat piece of metal or plastic sticking out of a slot, using a screwdriver, push this in and hold it in while pulling on the key, and the cylinder SHOULD slide out. After that buy a new cylinder (get it re-keyed if you want only one key for the car, and then with key at on position , push the cylinder back in so that that little piece of metal drops in the slot in the housing. Try the igniiton for a start and if all is good put the trim back on.