You've got to use every possible capability to get it to turn one last time to the #1 position. Use a vibrating sander...........play with the key........use some lock lubricant...........but, get it to turn one last time and don't turn it back.

The tumbler is shot and you'll need a replacement from the dealer.

If you can't get it to turn, you'll have to spend considerable money to replace the entire ignition lock assembly............a long and tedious process..........or a very costly one.