Edit Pages/Posts, tool bar and page options not working properly

Using Megazine Theme for site https://www.poorexplorer.com.
When trying to edit a page or a post the text is white and I cannot edit or click on either the Visual or HTML tab. The ‘tool box’ is gone completely and down the bottom I cannot edit the ‘page option’ or ‘post option’.

I have seen other forums from people who have had the same problem. I have tried:
1) Deactivating ALL plugins
2) Switch theme to Twenty Eleven
3) Edit a post (displays as white pane with red underlines)
5) Clear cache (press F5) – This fixed the problem, until…
4) Switch back to original theme
– Problem came back
Then I tried:
1. Install “use Google Libraries” plugin. Activated plugin.
2. Activate “Twenty Eleven” Theme.
3. Clear browser cache.
4. try the tabs, and everything worked.
5. Switch back to my usual theme
– Did not fix either

I am not very good at HTML so please when you give me any replies you’ll have to give them to me in Idiot Terms, otherwise I won’t understand. Because of this I have been hesitant to edit anything inside the database. Any help appreciated – Have not been able to edit my site in Months!