Depending on how you have your "Control Panel" set to show, either go to... "Control Panel"... "Ease of Access" then "Ease of Access Center" or "Control Panel" and then "Ease of Access Center".
Once in there click on "Use the computer without a mouse or keyboard".
On the next screen uncheck the box next to "Use On-Screen Keyboard" and then click "Apply" and then "OK". That should give you access to the physical keyboard again.