Have you tried running scan and repair? https://www.bungie.net/en/Help/Article/46501 If that does not work, try uninstalling Destiny, then uninstall the Battlenet launcher. Reboot your computer. Once rebooted, using a browser go to the Blizzard website and log in to your account. Then go into your profile and change your password. Log out of the site, then log back in with the new password to make sure it is working correctly. No, download the Battlenet launcher and install it and then login with your account name and new password. Install D2 from the launcher and try getting in.