I went to reply to a text message and the keyboard will not show up. I have restarted, shut down and removed the battery from my phone and I still can't get the keyboard to show up.
I recommend trying to find your keyboard app through Settings --> Applications.
Once you locate it trying clearing it's cache. If that doesn't work trying clearing the data.
It is hard to be specific here because I'm not certain which keyboard your phone is set to.
I went to Settings and my phone is set to Samsung keyboard when I try to go into the setting for the keyboard the screen goes black for a few minutes and then a message pops up that the 'Samsung keyboard isn't responding'