How do I restore the size of a display on the second screen on an internet site (See details)

I replaced my laptop and went from windows 7 to windows 10. I was familiarizing myself with it and trying to scroll down on a story on either fluther or google, I don’t recall which, using the arrow in the bottom right corner. I noticed the display screen narrowing until it was the width of a small ruler and completely unreadable. It’s stayed that way since then. Did I hit a zoom key or something else? it’s a slow friday and I didn’t feel like dealing with support just yet, so I thought I’d throw it out to the fluther community. No biggie, other non net programs work but any ideas? I’m on my desktop now.