Parent page changed to child page

Parent page (seniors site) looked after by somebody else, our site – the child page has been affected by them changing the parent page to a child page and now all our plug-ins have disappeared and SportsPress is not loading our pages. Does anyone have a solution where we don’t lose the rest of the data on our site? Can’t find where to install the plug-in again.

The page I need help with: [log in to see the link]