I have run into the keyboard suddenly not working in Kile on occasion. This is because there is some character length error which automatically enables Read Only Mode. To fix this simply go to the Tools menu and disable the Read Only Mode (should have a check mark) by selecting it with a click of the mouse. I went through some headaches with this before figuring out this simple fix from some help at KDE. I filed a bug report and received responses which pointed to this simple fix. It's always something stupid or simple, isn't it?