Cant Open Minecraft

When ever I try to open my minecraft, I will open the launcher and click play. But when I click play the launcher doesnt open up minecraft, it takes me to a blank game output page. No matter how many times i click play, no matter how many times i re-download the thing, it just wont work. This has been happening for over a week now. I really want to play but it just wont work! Please fix this!