I have downloaded the zip file and its not working

Sometimes the download remains incomplete (due to a connection error your download may halt, which can cause you to save the wrong file to your computer). This means that you only have a partial file cached, and every time you try to download it again your computer just pulls it from the cache. You need to purge all temporary folders on your PC ("c:/windows/temp", "c:/temp", "Internet Temporary files") and download it again to solve the problem.