Solved All Icons Changed To Vlc

I am using window 7 OS 64 bit.yesterday i opened one mp4 file,it asked SEARCH THE WEB FOR SOFTWARE THAT CAN OPEN YOUR FILE or OPEN USING ALREADY INSTALLED SOFTWARE.i choose open using already installed software an click vlc as default.after clicking this and i saw the desktop all the icons are changed to vlc,even computer shortcut also changed to vlc.how to change this.please help me