Try clicking on new profile, put in your username, and then put in your password.

 

Have you tried both your e-mail and IGN?

 

This happens to me a fair amount to me too, when I'm on my friend's computer. I just keep reclogging. There will probably be bug fixes soon anyway.

 

I wanted to talk to you. I was wondering if (when you get back on) you could flatten a town for me. I obviously will pay you well. I need this done badly. Please contact me back.

 

Did you migrate your account to a mojang account? That could be the problem. Cause then you would have to use your email to log in.

 

well just be sure you're typing your email or username and password exactly as they are. I don't know if theres anything else I can do to help :/

 

You could try changing your password, although it may do nothing.

 

:/ I don't know, try going to the help link it gives you.

 

Email mojang at the help link they give you, we can't really help you but they can. :p

 

I would recommend at this point to just get rid of all your minecraft files and .jar
After that try re-iinstalling minecraft from https://minecraft.net/