If your account is old, and you migrated your account in the process of changing your name, then you must use the e-mail associated with your Mojang account to sign in from now on.

^
Griffin, your account is migrated. You have to use your email instead of the username.

I just got back from a concert rehersal and it worked... wat
also lemonade I know I was trying to sign into my mojang account

Glad you are able to log on in your account again

Me too! Thanks <33