Try selecting “ File” > “ Save As…” and save the document as a “. You may have saved your document in a format that does not support the Equation Editor. Why is the equation editor selection grayed out? The Equation Editor will be available under the “ Insert” menu.
Click “ Close” when the install is complete.
You could also take the lazy route, and select “ Reset“, to set the ribbon or tabs back to their default settings. Select “ All Commands” in the “ Choose commands from” menu, then add “ Symbols” to the tabs listed on the right side of the screen. If you still do not see the Equation option, you may have to go to “ File” > “ Options” > “ Customize Ribbon“. Simply select the “ Insert” tab and choose “ Equation” under the “ Symbols” section. For Word 2016 or 2013, the Equation Editor should be available by default.