I have a 2001 nissan altima and the key turns freely in the ignition but doesn't start. HELP?

I have a 2001 nissan altima and the key turns freely in the ignition but doesn't start. The power comes on but it won't turn over its loose.|||The ignition cylinder is broken and must be replaced. You may also need to replace the steering column as well.|||On the Nissan Altima,the ignition lock and barrel,is all one unit.Just replace it and you will be fine.