Live contribution pages coming up blank
There have been a few questions on this site relating to:


CiviCRM not displaying pages under certain WordPress themes, or
CiviCRM showing only CiviCRM content - without the theme!


In particular I'd recommend checking out this question which, while it describes different symptoms to what you're reporting, may help point you in the right direction.

There is also a question on which WordPress themes are thought to work well.

My suggestion would be to try other "stock" WordPress themes first, and see if the page contents start appearing. If so, then you have a good reference point to analyse the problem. If not, then you might be looking at a CiviCRM bug.

Twenty Fourteen theme is a "core" (if older?) Wordpress theme that CiviCRM is likely to have been tested with. Other WordPress plugins might be a factor still, so if you have the same issue with all themes then look into the possibility that a plugin is interfering.

Some other questions which seem similar or related to issues with CiviCRM in WordPress themes:


The contribution payment verification page has lost the site theme styling
Why does CiviCRM render a validation failure without the Wordpress theme?
CiviMail Unsubscribe link goes to an empty Wordpress page
Wordpress Theme on Contribution pages (maybe)