Doors – Key stuck in Security Door

In its currently disassembled state, there is nothing locking the mechanism. You are correct that the C shaped half-circle shaft is what pulls the latch back when turned.

If you cannot push the latch back with your finger, the anti-jimmy device has had a piece break in it.

I had this happen on a bathroom door latch about two weeks ago, probably made by the same manufacturer as the shape of the lock actuator rod and latch actuator are exactly the same.

If you look at it, the lock actuator rod (the center piece you were turning) has a taper section just where it passes through the latch pull which means that during assembly, you manually push the latch back and it passes straight through.

In order to get clearance so the lock actuator rod will pass through, I pried the folded piece that they pass through till I got clearance so the shafts would pull out. I then squeezed the folded piece back together and pushed the latch out. It didn't even require taking the door off the hinges.

Replace the whole door knob/latch assembly with new and you're back in action.

Bathroom doors are for courtesy, not security, and are designed to be easily defeated. The solitary purpose of that hole on the end of the knob, and the button behind it, is to unlock the door.

Work that option quite firmly, straight in, with the stoutest thing that'll fit in the hole. If that doesn't work, into the trash it goes.

Since the lock-set is beyond saving, you can poke at the other holes in an effort to release the knob handle from the shaft, and otherwise destructively disassemble it in any manner that won't harm the door or trim. It shouldn't be long before you gain enough access to the mechanism to either spring the lock, or slide the latch. Throw the bits out and off to the big-box to buy a $10 bathroom lockset.