cannot log into the wp-admin of my website

If you have a valid username or email address, you can simply reset your password by clicking the “Lost your password” link at the bottom of the login form, no?

https://tateauthor.com/wp-login.php?action=lostpassword

I attempted to change my password, to no avail. It said that it was strong. So, I tried to change my username, as well. Both efforts were a “no go”. This is the exact, message I am getting: “You attempted to access the “Tate Author” dashboard, but you do not currently have privileges on this site. If you believe you should be able to access the “Tate Author” dashboard, please contact your network administrator. Once again the link to my author’s website is: https://thebelieversheart.tateauthor.com/wp-admin
Also, the username that was given to me, by my product manager, was gaynellhickman, and the password was gaynellhickman101.

Well now, the WordPress dashboard and controls have just disappeared, from my tatepublishing author’s website. https://thebelieversheart.tateauthor.com/wp-admin
Please, help!!!!!!!