I have messed up excel on my computer. The Upper set of toolbars: (under the
home tab a Paste, copy, text alignment, conditional formatting, format as
table, etc.) is gone. I have to press on the indented tab (home, inset, page
layout, references, etc) to bring a given toolbar out. If a click on a cell
after bringing a toolbar out, the toolbar automatically disappears.

What should I do to restore my previous settings?