Some of you may have noticed missing captcha after updating to Joomla! 3 and 2.5 versions despite it was working properly. Bug supposed to be fixed in 3.2.1 release however some may still have problem with this, such as myself when updated to 3.3 version.
How to fix missing captcha problem?
You need to change couple of lines in your plugins/captcha/recaptcha.php file – here is the solution:
https://github.com/joomla/joomla-cms/pull/2437/files
Some of you may find it easier to just replace the content of your recaptcha.php file.
ReCaptcha still doesn’t work in your Joomla website?
Make sure you actually enabled it in Global Configuration. In your Joomla administrator panel go to Global Configuration -> Site -> Default Captcha and set Captcha – ReCaptcha.