In order to reinstall this application, first you need to remove it from your computer. To do that, you can use the classical way by going to Start -> Control Panel -> Add/Remove Programs (Windows XP) or Programs and Features (Windows 7). If this method isn't working, I suggest you use a third party tool like Revo Uninstaller to force it to uninstall by wiping out all traces of its presence from the system. Also, it is advice to use AdwCleaner to make sure that there are no leftover rogue registry keys or toolbars in your system.
To download and install the latest version of this software, you can check Software Informer application's web page or the official website.