Not able to Resolve Broken Links

I have few broken links in my blog posts. I know what is the problem but I do not know where to go and correct it.

Example: In this page, http://www.infosearchbpo.com/bpo-news/tag/call-center-services/page/2/

this is a broken link, http://www.infosearchbpo.com/bpo-news/tag/call-center-services/what-is.php

I realize that what-is.php is wrongly linked, but I am not sure where I need to correct this linking.

Please help.