I am at my wits end with silverstripe. I just changed to a different page type in the admin area which made the admin content area to disappear, i have to reload the admin area to go back in, i can access all the other pages but as soon as i click on that page again in the site tree, the admin content disappears. So i can't even get to the settings to change it back.
All I did was change the page type.
Can someone help please.

See attached.

Have you checked for errors in that pagetype?

If there are, just fix them, do a ?flush=all and you should be able to access that page in the CMS again.

You can see the error that is generated using DevTools in Chrome or Firebug. If you are using DevTools, you can filter XHR in the Network tab. You get to DevTools with F12. XHR is another word for AJAX requests. You can then see the response and whether you get an exception which you probably will. Then you can debug your custom page type because it will tell you which line causes the error and fix it. Alternatively/additionally, you can go into the DB with PHPMySQLAdmin or similar and change the page type back manually. It will be in the SiteTree, SiteTree_Live and SiteTree_versions tables.