If Java has been disabled in your version of Firefox, please follow these easy steps to re-enable it (also Watch the Video ):
1. If you are running an older version of Java on your computer, the issue is easily remedied by simply updating your computer's Java to the latest Java version, which is free. You may wish to visit the Java web site to be certain you are running the latest version of Java.
2. You may also choose to use a web browser other than Firefox that does not have this restriction. However, we always recommend that you use the latest Java version, so that would be our suggestion.
Also See: April 4, 2012 Update from Mozilla
Also See: Unblocking the Java Plugin
Note: On April 2, 2012, Mozilla, the developer of the Firefox web browser, mistakenly hardblocked older versions of Java on Windows computers that use the Firefox web browser (please see this PC World article and Mozilla blog post for more information) instead of softblocking them. Mozilla has since corrected its mistake.