My WordPress installation was not showing the Post Editor. Basically instead of an editor, I had a box that I couldn’t type in.
I also noticed widgets that had drag and drop configurations, where I couldn’t do any dragging. On the “Add New Post” page, the “Add New Category” popup wouldn’t work. The Permalink “Edit” button doesn’t work.
Okay, something with my WordPress installation wasn’t running jQuery or Ajax properly.
There is a WordPress plugin that lets visitors to your site load Google’s cached version of jQuery, instead of loading it from your site. Faster for them (since it is probably in their browser cache already). Just install the Use Google Libraries plugin.
There is a page on why you should let Google host jQuery for you, http://encosia.com/3-reasons-why-you-should-let-google-host-jquery-for-you/
I have WordPress Multi-Site installed, so I went to the My Sites, Network Admin, Sites page, and from there to Plugins, Add New. I turned on the plugin for all sites (“Network Enable” ), and my editor and Ajax features (used a lot throughout WordPress) work now.
I also copied jQuery and TinyMCE from a fresh download of WordPress to my site. They are in your wordpress\wp-includes\js\ folder, and go to the corresponding folder on your site. I used FileZilla’s Upload “if different size or source newer” option. (If that doesn’t fix the problem, try copying the entire folder, overwriting all files.)
The Post Editor is working, both Visual and Text modes. The “Add New Category” link doesn’t work yet. The Permalink “Edit” button is not working yet.