Login Failed

I am not able to log into my Minecraft account in the application or online. It says incorrect username or password but I am 100% sure that it is correct and I have changed it multiple times. I have tried waiting for the 24 hours but nothing happens when I try it the next time. IF possible I would like to either get the game to work or a refund so that I can try to purchase the game again with it working. Thank You.