My chrysler sensory key?

My chrysler key has been acting up and now it is locked and won't start up. The Steering wheel is not locked, but when I put the key in the ignition it just wont turn either direction. I have a 1999 Chrysler concord and somebody told me that it has a sensor in it, but its the same key I have been using. Please HELP!!!!!! I need to get home!