When I open the launcher it doesn't look like it would normally,when it comes up it's just a small white screen named launcher and it has a loading bar in the middle and it says downloading runtime,why is it doing that when I had minecraft before it looked normal but yesterday when i downloaded the launcher it did that.Help please
From your description I think the launcher is doing exactly what it's supposed to do, updating. The Minecraft launcher does update. And about the unable to update part, I have no idea what that is about but I pulled this from somewhere about someone with the same problem:
Go to C:\Program Files(x86)\Minecraft\tmp and rename the .tmp file to MinecraftLauncher.exe copy and overwrite the MinecraftLauncher.exe file in C:\Program Files(x86)\Minecraft with the renamed file. restart the game, let it run through its course and the game should start from there, mine did and I was very glad.
I recommend you try it out.