Lost Password/Unable to retrieve

I am a true novice at this and have begun to install in Xampp as a test model. I got the success screen and entered my new login information. I used the email that I WILL have when my website is complete (doesn’t yet exist). When I was unable to login the first time, I attempted to retrieve my password. It is being delivered to an email that doesn’t yet exist. I am clueless about how to retrieve my password…and when I attempted to set up a new account, I am told my information already is assigned. HELP!