In Print Layout view, Word displays a “sheet of paper.” Each onscreen border represents the edge of a single sheet. Sometimes, the top and bottom margins seem to disappear.
This isn’t a phantom gremlin; it’s actually an obscure feature that’s a bit too easy to engage. Word lets you hide the white space (including the headers and footers) at the top and bottom of a page, thereby fitting more content on the screen.
It’s a helpful feature if you need it, but if you don’t know it exists when your margins suddenly disappear, you might feel a bit lost. You won’t know why the margins are gone or how to get them back.
When you move the mouse pointer to the top or bottom edge of the page, Word changes the mouse pointer to a small icon with two arrows pointing toward each other (up and down). If you click that icon, Word hides the white space at the top and bottom of the page. It only seems that Word removes the top and bottom margins.

The good news is that it’s just as easy to reclaim the white space as it was to lose it. Hover the mouse pointer over the top or bottom edge of the paper and click the double-arrow icon again. The icon toggles the white space. Word 2007 has the same feature, but you must double-click the icon, which makes it a bit harder to accidentally engage the feature .
Word displays the white space by default, which is how most of us work. You can change that behavior if you like. From the Tools menu, choose Options and then click the View tab. Uncheck the White Space Between Pages (Print View Only) option in the Print And Web Layout Options section. Doing so will hide the white space by default. The icon will still work to toggle between display settings. In Word 2007, click the Office button and then click Word Options. Click Display in the left pane, check or uncheck Show White Space Between Pages In Print Layout View, and click OK.