Visual Tab Missing From Editor

The visual/ text tabs have vanished from tinymce. I have tried everything I could find on the web and nothing has worked:

Deactivate theme
Deactivate all plugins
stop concatenation of scripts

debug-scripts (no errors)
no js errors in admin

Is there any DB setting which could be causing this?

Just in case anyone else is having this problem, I’ve found that a pretty reliable way to get your visual editor tab back after upgrading to WordPress 4.0 is:

1. disable all plugins
2. Change the theme to one of the defaults (e.g. TwentyFourteen)
3. Go to “my profile” and check the “disable visual editor” box.
4. Save
5. Go back to “my profile” and uncheck the “disable visual editor” box.
6. Save