I got an email today for a reader that reminded me of one of easiest ways to accidentally ruin your day with a bad keystroke. He wrote:
“Today when I tried to add a phone number to my spreadsheet, it refused to print and moved me up to the above cell. I tried a new spreadsheet, and the same thing happened, it showed my letters but refused to show my numbers.”
Before I had a chance to answer, he wrote me back and said he’d realized that he’d hit the Num Lock key. When you hit the Num Lock key, you lock the number keypad into place. That’s great if you’re using it to do calculations, but a problem if you want to use arrow keys or the Page up or Page Down functions.
Another troublemaker can be hitting Scroll Lock. It does what you’d suspect, it stops you from scrolling.

It’s a good reminder that when something goes wonky on your keyboard, make sure you haven’t accidentally hit the wrong keys before you start thinking something is really wrong with your computer.