Login always redirecting to homepage?

Hello all,

I have just started moving some sites from one hosting service to another. When I did so one site had a problem. When I go to the login page and click login it takes me to the homepage no matter what I type. I cannot confirm if this was a problem before or after the migration. I also do not want to try and disable plugins as the only way I can is via ftp and the site is live. If that is the only way to trouble shoot this then I will.