you may need to reset your account. I got a Home Access Center account reminder email from my school along with the registration reminder emails for each kid(cuz I'd never been able to finish account activation at the beginning of last year and got sent in circles by the school and the administration offices. ...anyway...). The HAC email had my uername and then a list of links including login, password reset, and account reset. I did the account reset.
if you don't have any recent HAC emails, put Home Access Center in your email's search bar and look through any for your login info and account help/reset links.
if not, you could try this: my school's username format is g-[first initial][middle initial][lastname], try that in the username, then like... type whatever in the password field and submit, and it'll give you an error and ask if you want to reset your account. I also had to do that because I have two different accounts for some reason and the second one's saved password was incorrect.
If like me, you also inexplicably have two accounts, you could try the username format for my second one: