Let’s say, you’re entering CSS or JQuery in a Content Editor in your page so certain parts of it are hidden and all of a sudden, you realize whether by accident or on purpose, you’ve hidden the Site Actions menu, so there’s no way to edit your page. Have no fear – –

All you have to do is to add this query string to your page URL:

?ToolPaneView=2&pagemode=edit

Now you’ll be able to edit anything on the page.

Another way is:

?ControlMode=Edit&DisplayMode=Design

There is one other way. All you need to do is to ‘View All Content’. Choose the folder where your page resides and check it out. You should be able to click on the page and edit it.