Quick advice to the OP: give up.
Even if the site is still active today and is willing to give you the bitcoins you claimed years ago while too valuable right now, you may not be able to recover them because you have lost access.
There might be something fishy about it. Back then, too, frauds were prevalent. They are much more pronounced today, but they were there. You should ask Microsoft Support to help and guide you with that. Email address.
I doubt that bitcoin was the target of scammers back then, it was a disproportionate effort because bitcoin was not very valuable and in circulation was much less than today. It will bring scammers at high risk of being caught.