Upgrade to the latest version of WordPress (as of this post — WordPress 3.5) and notice that the post toolbar that contains buttons such as bolding, code, quotes, etc — is gone?

How about the Visual tab — is it disabled?

Unfortunately, this is what can happen on some websites that have upgraded to the most recent version of WordPress. You can fix it, however.

If you do NOT use the visual editor, then you can fix it by going to USER -> YOUR PROFILE — and then check “Disable the visual editor when writing” to disable the Visual tab. This will bring back the toolbar, oddly enough, but you will lose access to the “Visual” tab.

If you want to keep the visual tab and fix it, then first you should disable all plugins and see if the toolbar comes back. If it DOES, then enable all the plugins again and one-by-one you will need to disable each plugin until you figure out which one is causing the problem (one or MORE plugins may be incompatible with the recent update, thus causing the issue). This can fix the Visual tab if it is greyed / grayed out and not working, as well as the toolbar issue.

Hopefully this brief guide helped you to fix or troubleshoot your WordPress problem. It’s a strange bug / error, but fixable.