Home laptop settings changed mysteriously

I like having my multiple page tabs up top. Something has mysteriously changed what I'm used to. In the pic, see how the tab is at the top middle? I'm used to a tab at the top left with a + sign to the right of the first tab to click on to open another window. What has happened? Earlier my wife sat down here at the laptop, half delirious after getting out of the hospital. I know that she wouldn't even know what she has done. Any quick help? I have to run out to Wal-Mart to get her a shower stool. I'll check in later. Thanks guys & gal.
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