Might seem simple, but if you’ve never logged into WordPress before, it can be difficult to find the correct URL.
It’s important to remember, WordPress.COM and WordPress.ORG are completely different website setups:
WordPress.ORG is a free, self-hosted content management system. If you don’t remember setting up WordPress (or hiring someone else to do it for you) chances are it is a dot Com installation.
WordPress.COM is a website managed and maintained by the creators of WordPress. If you signed up for WordPress, and paid a small fee, you will want to login here.