Before going through these steps, please ensure you’ve tried to log on using the ‘Enter your existing site address’ login screen. That login form includes your Username, Password, and Site URL. You can find instructions on how to log in with your self-hosted site here.
If you’re running a self-hosted installation of the WordPress.org software, connection issues are typically caused by one of two things:
Please follow those links for more help troubleshooting those issues.