NOT ABLE TO JOIN ANY SERVERS

So I go on Minecraft like I normally do, and when I joined a server it just kept saying Failed Bad Login. I tried to go on my own server and it said the same thing! I tried I joining my server over and over , and then I said communication error! Like how's that possible! The server is being hosted on my internet connection, on my computer that has really good internet, and great internet speed! I tried logging in and out, but it didn't work. The same thing happened to my cousin, but he can still go on his server. I need help!!!!