Launcher Unable to Locate Java Runtime

Every time i would play Minecraft, the java "generic icon" that would pop up when the game starts bugged me, so i changed the icon, but the file was still named java, so i changed the file name from Java to Minecraft, and when i went to play it would say that it can't locate the file. What I think happened is that the Launcher can't find java, i would change it's name back but i can't find the file anywhere, i tried reinstalling both java and Minecraft, nothing worked still won't start