Any one suggest me to find source codes
 

Can any one suggest to find me source codes for application that run on a computer, googled it but cudnt find appropriate answer

I need to familiar with my application in and out, so like to study source codes, for eg: vlc player

Just go to the package's website and you should find a link to download the source package. For example, VLC --> http://www.videolan.org/vlc/download-sources.html