Let’s say that you know beyond a shadow of a doubt that you have created a table on your SharePoint page, but you can’t see it (the GridLines, in editing mode) in order to add content. This entire tip is based on editing in the browser.

First, it’s probably because you have set the style to ‘clear’ in the Design tab of the Table Tools. To regain the GridLinesfor editing purposes (not visible in the page itself), just go back to the Layout tab in the Table Tools and click on the ‘Show GridLines’ button.