Handling switch over from one window to another using Selenium Webdriver

This script helps you to switch over from a Parent window to a Child window and back cntrl to your Parent Window

String parentWindow = driver.getWindowHandle();

Set<String> handles =  driver.getWindowHandles();
for(String windowHandle  : handles)
{
if(!windowHandle.equals(parentWindow))
   {
     driver.switchTo().window(windowHandle);
      <!--Perform your operation here for new window-->
driver.close(); //closing child window
    driver.switchTo().window(parentWindow); //cntrl to parent window
    }
}