The screen will freeze on Mojang (when i click play on the minecraft launcher)

When I click play minecraft 1.12 it starts up, but when it gets to the Mojang screen it freezes. And then when i try to click out it says, "Minecraft 1.12 is not responding." So, when i finally exit out it says that Minecraft 1.12 has crashed. And this just started, about a week ago i could play minecraft with no problems. Now it doesnt even let me play.