Windows 8 has added a new bar called the charms bar instead of taskbar and it is missing the start button. This bar has changed how the the people used to navigate in windows. And most of people disapprove the absence of start button .Here is the way you can get it back you just have to make some changes in registry file.
Making changes in the registry file will also revert Windows 8 Metro UI, Windows Explorer, and Task Manager in Windows 7.