Won't shift into park?

When trying to shift into park the light on the dash that shows what gear you are in doesn't light up on park and vehicle will roll as if it is in neutral. Also can't get key out of ignition. After turning off and on a couple times and continuing to try to get it in park finally went into park, light lit up, and key came out. This was yesterday. This morning everything worked fine but it happened again this afternoon. Any suggestions on what could be the problem.