I have to admit I am not understanding what specifically your issue is, but I would like to help. A couple of things:

1. Shadows of Angmar is not sold any longer, but you can download and play the game for free here: https://www.lotro.com/en/game/download You should be able to log into your old account using your old credentials.
2. The web site where you list the game as no longer for sale is not an officially-supported vendor. If you are having any issue with a purchase through them, you will need to seek out their customer service.
3. LOTRO.com continues to have issues that will need to be addressed with a longer-term web site update. However, you should be able to refresh the page after login and be logged into your account. If the issue is you can not log into the game client with those credentials, that is a customer service matter. If you can log into the game but not web site, that is a different issue, so let me know.