You’ve probably noticed that, when you create webpart pages, there is no Quick Launch navigation area on the left. Some of you might find this a little irritating and are wondering how you can change it so you have it show.

There’s a 2 step process in order to get the Quick Launch back.
First, there’s a style block inside the ContentTemplate area of this tag:

SharePoint:UIVersionedContent 

In the body selector of the style, change the display from ‘none’ to ‘inline’.

Secondly, totally remove the ContentPlaceHolder with the id of: ‘PlaceHolderLeftNavBar’. It’s empty anyway, and its only purpose is to override what would normally be there – the Quick Launch.

That’s all there is to it. Once this is accomplished in the page, your Quick Launch is back.

(I would definitely recommend though, that BEFORE you start editing any page, you make a copy/backup of the page, just in case something goes really wrong)