Hello, mmlabbd, & welcome to the WordPress support forum.
Firstly, a site url in these types of situations is *most* helpful.
Please log into your dashboard & activate the twentysixteen theme, or whichever default theme you wish. Next, please reset your plugins folder by renaming it, either through your hosting provider’s control panel or via FTP (& hopefully secure FTP). Appending a .old or a 1 to the plugins folder name is fine. Next, please clear your browser cache, log into your dashboard, & see if your widgets and/or theme customizer loads.
If it does, then what you’ll need to do is to rename your plugins folder back to the original name, but go into the folder itself & rename all the folders in there except for 1. I recommend plugins like Akismet or Jetpack as good candidates not to rename this first round, since they’re written by WordPress developers and thus should theoretically have a high degree of compatibility. Again, clear your browser cache, log into the site, & see if your customizer loads. Keep repeating the process of renaming a folder at a time, clearing the browser cache, & logging into your site & loading the customizer till you find the plugin that is causing the conflict, i.e., the last plugin you renamed before the customizer won’t load is the culprit.
If renaming your plugins folder, as in my initial step, does not solve the problem, then some additional troubleshooting steps are necessary. Rather than going through those now, though, how about you try this & give a report back if that worked, & also a site url if it didn’t.
Thanks Jackie, I did that and it was the Yoast SEO plugin! Right at the bottom of my plugins list, that was causing the problem. Disabled it and the site is working as expected.
Glad we could help, mmlabbd, & thanks so much for marking the topic as resolved!
