Ignition staying on, stuck in place, will not start or turn off.

What is your question?

Went to move the car last night, put key in as usual, it turned to ignition, lights on and then nothing, the ignition is stuck on, the barrel is locked in place and if i wiggle it the barrel spins but doesn't start or turn off. The car was working perfectly before and is usually really reliable, it is low mileage and hasn't been modified in any way that I know about, it may have an after market alarm. Thanks in advance for any assistance.