Just SharePoint

There have been significant changes to the user interface (UI) for Microsoft SharePoint Foundation 2010, including the addition of the Ribbon. By default, the v4.master page includes the Ribbon. Many of the commands previously found in menus and toolbars now exist inside of the Ribbon. As a result, if your existing master page does not contain the Ribbon, many commands will be unavailable.

Read the article on how to add the Ribbon along with any new controls or content placeholders that are required for an existing master page to render correctly in SharePoint Foundation 2010.

Source article and code available here

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