If it hasn't locked the steering wheel, and you need to drive it. A temporary quick fix will put you on the road.
You have to remove the cardboard panels under the dash to gain access to the back of the ignition. The switch part of the ignition can be removed easily from under the dash. (2 screws) If the steering wheel has locked, this trick is not advised. You can start and stop the engine by turning the now unattached switch with a large screwdriver blade.
When time allows, you can remove the steering column surrounds and gain access to the lock, which can be pulled out after you punch out, or drill out a small pin in the bottom. Then you can sit down at the kitchen table and figure out how to fix the lock. Use the search and you should find plenty of posts for similar problems.
Mike in Beavercreek has a good write up on the lock. Email him and he will send you a copy.
Similar post http://www.bmw2002faq.com/component/option,com_forum/Itemid,57/page,viewtopic/t,344086/highlight,ignition+key/