cyberbore on "Text editor using half-screen, Visual not working"

The TEXT editor is coming up in a reduced box in the editor window and the Visual Editor button doesn't work.

See a screen shot here:- http://www.t5.cmsmadeeasy.com/WPeditor.png

Details:
WP 4.5.3
ZeroGravity Theme
Chrome 51.0.2704.84 m on Windows10
(Same issue on Safari with Apple)

Having read various threads, I have tried:
Reinstalled WP twice; tued visual off/saved/on in User; deactivated all plugins; switched to standard theme; installed Wordfence; tried adding code to config.php

None of it made any difference.

Please look at my screenshot on the link above and if you can tell me how to solve it, I would be most grateful.

To rule out any theme/plugin conflict, try:
- deactivating ALL (yes all) plugins temporarily to see if this resolves the problem (plugin functions can interfere). If this works, re-activate them individually (one-by-one) to find the problematic plugin(s).
- resetting the plugins folder by FTP.
- switching to the unedited default Theme (Twenty Sixteen, etc.) for a moment using the WP dashboard to rule out any theme-specific issue (theme functions can interfere like plugins).
If that does not help, then I recommend asking in this theme's dedicated support sub-forum for better results so its developers and users can help you with this:
https://wordpress.org/support/theme/zerogravity

Tara,

Thanks for taking the time to respond to my cry for help - much appreciated.

As you can see from my post, I have tried the things you suggest, with no success.

In particular, tuing off all plugins and / or using the unchanged 2016 theme make no difference.

I am doing as you suggest and trying the theme's own support, but it doesn't seem to be theme related - but who knows!

Thanks again,
David

- Your browser can help you identify JavaScript issues or conflicts. Do you have any Javascript errors in the console when looking at the editor page? - This article can assist you in doing that diagnosis.
- If you use any caching systems, like Cloudflare, clear those caches.

Tara,

I have solved the problem.

I took a new, clean WordPress installation on another URL and ported the site over. That worked well in vanilla WP. I then added all my plugins and widgets. That worked.

I then added the two themes I've been using and that worked!

So it looks like it was either the WP installation or something to do with the server set up. I'm not trying to find out which...

Thanks again for taking the trouble to make your suggestions.

David