How to bring back the control to already opened web page from a newly opened web page after that.Help me plz

I don't understand what you're asking. Is this an ASP.NET web application where you're trying to navigate back one page, or do you have mshtml embedded in a desktop application and you're automating the navigation?

Please take the time to post exactly what you are trying to do and not fragmented questions.

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Close that newly open window.

consider there is one web page let we call it Master there is one field (enter code)
and link button near (by click) it will pop up anothere webpage let we call it child which contain a gried showing all the details(code,name so it will be easy for user to select) ,if user click on select (response.redirect take place and
i need to have the code in the master web page field(enter code))
The problem i am facing is the response.redirect is opening a new webpage (rather than going to already opened master).