Website hacked and can't log into wp-admin panel

My website: https://www.sprokkelster.co.za was hacked. The index.php file and functions.php files were replaced with new ones.

I have fixed the problem and the site is working again, but I can’t log into my dashboard. When I click on lost details and type in my username or my password, I get the following response:

“The e-mail could not be sent.
Possible reason: your host may have disabled the mail() function…”

I can still log into one of the editor’s dashboards, but not into the administrator’s dashboard. The administrator’s account is the account that was hacked.

I really don’t know how to get back into my administrator’s dashboard.

Does anyone have any advice?

Kind regards,
Suzanne