Leave Reply link problem

Hi everyone, I am having terrible problems with my blog and am not sure what changes caused the issue – The first change was updating to 4.2.2 WP and the other change was installing a plugin from BestWebSolutions for a Captcha.

The problem is that the leave reply link just causes to the page to scroll to top with no facility to leave a reply. I deactivated the plugin but the problem still remains. I read to try changing theme but that has not made a difference. I am stuck as to what to do next.

All help is very much appreciated.
many thanks
Darren