Occasionally this happens to me on my '87 Westy.  It's usually seems to occur
when I park such that the wheels are slightly turned and bind up the steering
wheel a little.  When the ignition is off and the steering wheel is turned a
little, it locks.  If it locks while bound a little, the ignition key will not
turn.

Turning the steering wheel such that some of the stress is relieved on the
steering column tends to allow the iginition to unlock.  Do this while trying
to turn the key.  It just takes some jiggling/playing to get it to unlock.

I figured this out once on another car after not being able to turn the key and
not wanting to break the key off in the ignition, I had it towed to my
mechanic, who promptly put the key in and cranked it right up.  Had to pay 50
bucks to look like a complete moron.

Hope this helps...........

> Suddenly, my ignition key doesn't want to turn some times when I try to

-- 
- Greg Daughtry -