The nexus currently doesn't tell you when a account is taken. But, however, if you get no error message and the OK button highlights, most likely, the account is taken.
If you played years ago, it could be still under your name, visit,
http://stellarfrontier.net/forgotPass.php to get your current password reset. You can then go to
http://stellarfrontier.net/nexusLogin.php to change your password and view some stuff about your current account.
If this still fails, PM me the name and email and I will check it out. But mostly if you still have your emails you should be ok to use the forgot password utility..
Mobious made it awhile ago but not many know about it
