Hi, I would contact your host to see if they can help. This definitely isn’t a theme issue, as there isn’t anything inside of the theme that could cause something like that to happen (unless you added something by mistake).
Your hosting company can revert your site from a previous backup that was working properly.
If they don’t help (they should) then I would try switching to a different theme like Twentyfourteen or any of the default WP themes and see if your Visual Editor works then. If it doesn’t and the problem still exists, then it is an external issue. Try and deactivate all of your plugins until the issue is resolved.
You could also activate the Genesis Framework itself as a theme and see if it works.
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