Our passwords are now case sensitive, so if you created a password with a capital letter in it anywhere, you must always use that capital letter. You also need to log in with the email address associated with the account, and any mistake in typing that would also cause the error you're getting.
I'm not showing you active for a couple of years now, but I believe this is you: Naridin
Given the time frame since your last access, I'd like to suggest that you clear all your old AFF cookies, clear your browser's cache and history, and log out of AFF, even if you don't think you're logged in. Close the browser completely, and then restart the browser and try logging into AFF. We changed our domain name slightly, and you may have some outdated cookies that are interfering with the login.
Other than this, DG will have to help.