White script in visual edit

HELP!! For some reason I cannot see the visual editor on my pages,.. the script is WHITE! I have search the forum and most answers for this are old and advise looking for a css line that is not findable anymore. ??

I’m fairly new at this but at this point do not know how to find the coding to change this, or what to do to correct the problem.

When I run a speed check, NextGen is running terribly, one error message I found is sections couldn’t load because Mime type “text.html” should be “text.css” I searched the coding and cannot find a line w/ Mime…

Anyone please have a fix for the newest WP version please?? Thanks!