Keyboard Suddenly Stopped Functioning

I was in the process of typing a name for a new folder. I had depressed Shift & D, when a dialog box quickly flashed and the keyboard will no longer function once logged in. It works for the log in, but nothing beyond that point. In addition, it works fine on the Windows side. I have checked the keyboard settings and changed the layout settings to see if any would make a difference and rebooted several times. However, all have been unsuccessful. Any assistance would be greatly appreciated.