i have already reset my password using the site, but i sign in using this instructions
Select Settings from the main menu (select Preferences… from the Opera menu, if you are on Mac).
Select Browser from the sidebar.
Under Synchronization, click the Sign in… button.
i receive a message "please try again. alternatively reset your password or create an opera account"
Do you type in your new password, to make sure it isn't trying to use the old one?