The thingie which makes the doorknob work jammed, so I was unable to open the door to get out. I was also unable to telephone for help, as I had left my phone in the living room. Frantic jiggling did nothing. My only options seemed to be to email for help or scream out the window.

But then I remembered that my emergency supplies, including a screwdriver, are in my bedroom. Granted I had assumed "emergency" to be something a little more far-reaching than "trapped in bedroom by jammed doorknob," but an emergency is an emergency. I unscrewed the plate, but that failed to free the knob. But I was able to manually push the lock thingie down, releasing myself. My landlord is fixing it now.