In Windows, click on Start | Control Panel | Accessibility
Options | Keyboard tab | uncheck the "Use FilterKeys" and "Use
StickyKeys" boxes | OK.

EdCook wrote:

I inadvertantly changed my arrow keys to single action, making it necessary
to hit the key each time I want to move it. How do I reset the original
action of moving the cursor by just holding down the key? The change affects
both Word and Excel.