Sure, just send us a message in Intercom (the chat bubble in the bottom right corner on desktop), or send me a private message, and I can probably figure out a way to get you access again.
I also edited your question to have a less massive title and move the majority of the (long) question to the body instead.
I'm now logged in, for the first time since the new LessWrong has been operating. Ages ago my old account (Stirling_Westrup) simply stopped working, and I couldn't log in to post a message saying there was a problem. I ended up making a second account, but never got any responses to my complaints that my main account was broken. On a whim I tried to log in now, and was told it was a legacy account. So, here I am. But is there any way to get back my original account Stirling_Westrup?