When I try to open up my minecraft launcher a popup comes up and says downloading runtime, it only loads until there is a few mb left to load but then another pop up shows up and states that it is unable to update the minecraft launcher. I tried restarting my minecraft, re installing it and updating java but nothing has worked. If someone can help that would be greatly appreciated.
Have you modified your Minecraft version? If yes copy your current .minecraft folder(C:\Users\yourusername\AppData\Roaming.minecraft) Obviously replace yourusername with your username for windows. For Mac or Linux see the following website http://www.howtogeek.com/207484/how-to-find-your-minecraft-saved-games-folder/
Then reinstall minecraft and java (completely), and try it out.
If that doesn't work, you may have a problem with your PC and could have a virus. If that is what you end up with, go to the stack exchange with that type of Q/A.