Start off by bringing up the Onscreen Keyboard by mousing the All Programmes list and finding it in the Ease of Access list, in case you need it but you might find the mouse or trackpad will do.
Go into Control Panel>Device Manager and right click on the Keyboard section. Choose Properties and hope you only disabled it. Reverse that and it shold work.
But!! If you're running WIndows 10, Microsoft has made it harder to get to the Control Panel and you have to use the Onscreen keyboard to point at the Windows key and R at the same time. It can be done. In the Run box that shows upm type
and hit the Enter key.