In order to rank up, you'll need to have merits and activity. In summary, you slowly gain activity points for staying active and merits for making useful/helpful posts.

This will guide you: FAQ: Everything you need to know about forum 'activity, account ranks and merit

As for your old account, it may got compromised, at least if you don't remember what you did. I advice you to stake your address and be able to prove the ownership of your account in the future.