Minecraft Forums

So yesterday I was playing minecraft perfectly fine. But now all of a sudden the game wont work. MC launcher starts up normal, but when I click play whats supposed to be the mojang screen comes up in a small window, but its just a blank white screen. It closes then quickly reopens to the same screen after a few seconds which is followed by another crash bringing up th MC launcher again. Minecraft doesn't give any crash message like it has to me before, it just shuts offthen reverts back to the launcher. I'm running 1.7 btw and the launcher says 1.4 at the top if that helps. Does anyone know what to do?