Hi @maya90,
It looks like you figured out how to get to your account, I apologize for the struggle. In short, several months ago, Sitepoint switched to a Single Sign-On to bridge between Sitepoint Premium, the Forums, and whatever else they may have in mind in the future. No need to worry, having an account is free, it is just a matter of where the credentials are controlled.
As such, with implementing this feature, the passwords for all existing users were no longer valid and users were instructed to go through the Create an Account process via Sitepoint Premium and to use their forum e-mail address so it creates the association automatically for them at registration.
If you have any additional concerns or questions, I’m happy to try and answer them for you, or at the very least, direct someone from Sitepoint here to answer your questions.