If the steering wheel is locked and the key is able to be turned all the way (should be the case since it sounds like you were driving when it occurred), the only suspect here would be the lock itself on the column. If the symptoms are typical of a steering wheel lock (some movement one direction but very little; no movement the other) and definitely not anything jammed in the steering rack etc, you will need to remove/replace the lock housing.
If the steering wheel and column covers are removed, you will see an aluminum housing wrapped around the column, this is the lock housing that holds the ignition cylinder and switch etc.
On the top of the lock housing you will see two smooth head bolts... these are snap to torque bolts where the head breaks off for security when they reach torque. You can use a drift and a hammer to remove these or you can take a die grinder and cut slots in the them then use a flat head screw driver to remove them (They are not tight).
With the accessories all removed, unscrew the bolts entirely and remove the lock housing and confirm the wheel turns. If it does, check the lock action in the lock housing while working the key (The lever that protrudes into the column is likely stuck).
If the wheel does not turn after housing removal, then the wheel lock is not the problem and you will need to isolate between the column and the rack by paint marking then unhooking the lower steering shaft from the rack (through the footwell area behind the brake pedal). If the wheel now turns, the problem is the rack; if the wheel still won't turn, the problem is the column.