I was using my phone one minute, and the next, the keyboard disappeared. Now, I don't mean that I simply can't access it. I mean *poof* gone, vanished, uninstalled, completely missing as a feature of my phone.
I did a soft reset (power on/off), hard reset (battery out/in), and it turns out that I missed an update, so I downloaded that as well. The keyboard is still missing.
I have yet to try reformatting my phone. I am trying to avoid it if possible, and besides, the keyboard seems like something of an integral part of the core software, so I am not yet convinced that it will even do anything.