Some tool tabs in Word 2007 are context sensitive...they only show up if the item they edit is selected. Context sensitive tabs are usually a different color, such as orange, yellow, or green.

For instance, insert a shape, then select it. The "Drawing Tools/Format" tab is visible. Click somewhere else on the page to deselect the shape, then the tab disappears.

I'm not quite sure what your friend is trying to do and what exactly disappeared, so that is the only advice I can offer.