Commonly, a key does not turn in its ignition if the steering column is jammed or the car is not in park. Other reasons for the car key not turning include the ignition lock cylinder being clogged with dirt, the key being damaged or the ignition being broken, according to Stu's EZ Auto Remotes.
If the steering column is locked, a normal occurrence in older model cars, jiggling the steering wheel back and forth while trying to start the car solves the issue. If the key still does not turn, the driver should check to be sure that the car is in park. If the car is not in park, it will not be able to start.
If the car is in park and the key still does not turn, the driver should clean and lubricate the ignition lock cylinder (the part of the ignition the key is inserted into). Electrical contact cleaner is made for this purpose and clears away dust and build-up that clogs ignition lock cylinders. In addition, if the key is bent or damaged in any way, it will not be able to start the car. In this case, drivers must have a new key made. In the end, if the new key still does not turn, the ignition itself may be broken.