Minecraft Launcher constantly preparing

I open my Minecraft Launcher click play, on latest version, and for hours it has just sat there saying preparing. It just sits there, no bar meaning its working, nothing, just blank. I have tried to repair Minecraft, I have uninstalled and reinstalled, I have logged out then back in. Closed and reopened Minecraft launcher many times. I have tried to play other versions. I am unable to play and I feel rather disappointed.