hello Soumya84, from now on firefox will block every version of the java plugin per default - this step was taken because of oracle's bad security record in the past (sitting on unfixed vulnerabilities for months).

you can enable it on a per-demand basis though: How to allow Java on trusted sites

Thanks for your reply, Philipp. But this ain't solving my problem yet. Actually by clicking on the plug-in icon, there are two buttons showing, one is 'Block plug-in' and another is 'Continue allowing'. I clicked on 'Continue allowing', but nothing worked. A preview has been attached. Now How can I solve this?

what version of java is displayed when you go to https://www.mozilla.org/plugincheck/ (it should currently be java 7 update 45 - if not try to download it again from java.com).

if java plugin content isn't playing despite you have allowed it from the icon in the address bar please also make sure, that you're not using an addon like noscript, adblock or others that might also block such content & you may need to accept all security-related messages that come from the java plugin itself...