My iphone 4 keyboard won't work?

This morning i woke up and found out my keyboard won't work anymore. Its only the top row but slowly spreading to the rest.Plus it won't let me answer pop up's.

Ok, so first go to <settings<general<keyboard and add a random one and delete the English, then restart your iphone, and go back and add the English, it should work, if it doesn't, it might be from wear and tear, and you might have gotten water into it.