old web pages Error

I did a migration from one web site to another in word press. I then deleted many pages and made new pages. Now in Google tools it says that I have errors and pages missing. I see you have a box that says click to put all pages in robot.txt not listed in site plan. Will this fix the problem errors for deleted pages and if not what should I do?Thanks Jay

http://wordpress.org/extend/plugins/sitetree/