Settings/Controls/Language and input. What keyboard do you have as the default? If it's some app that runs on a PC, or a remote keyboard, and it's not connected, you'll get that.
Or the keyboard (it's just an app) might be corrupted. You can install Swype, SwiftKey or any of the ones at the Play Store and set one as the default. You might find one you like better than the default Samsung. (I use SwiftKey almost always.)