Hi. Would you please write back and word your request differently and supply a photo of the broken plastic piece? I'm not sure what went wrong but the key cylinder should have slid into the lock housing the same exact way it came out. You should have carefully removed the lower and upper trim cover (behind the steering wheel). The battery would be disconnected before you turned the ignition key to the start position and then with a small punch or pick, depress the security lock "Release" button. Now the key cylinder would release and slide out and you would align the new cylinder and slide it back into place exactly how the old one was orientated. Please write back and be as detailed as you can. Tell me what happened. At this time I can only guess that the lock cylinder is not all the way in place. I hope this helps. If not I hope to hear from you soon. Good Luck.