Ask HN: How do I prove that a certain Gmail account does indeed belong to me?

Ask HN: How do I prove that a certain Gmail account does indeed belong to me?
25 by sebkomianos | 18 comments on Hacker News.
I understand that this submission might not be one of the best for Hacker News, in terms of knowledge shared, but along with the gmail account I am talking about and two or three other websites/communities, HN has been one of the longest-living places I find myself at in those ~15 years that I have been online. So, trying to avoid unnecessary details, here's the story: On Monday morning I signed in to my gmail account from a print shop in my hometown in order to access an email that was sent to me and print an attached document. I logged in from one of the shop's desktops, printed the document and then I tried to sign out from my account. However, I, at first, got a blank page and I had to reload it in order for the process to be completed. Since then, I have been unable to log in to my account because of a wrong password and when I try "recover account" I can't prove that I am its real owner as I can't seem to recall the exact month that I created it, more than 10 years ago (2007)! However, if I was given the opportunity I would be able to give a very detailed description of the contents of this account in terms of emails received and sent, labels, folders, etc etc. Now, apart from this gmail account being the centre of my control for all of my profile in different websites, forums, newsletters, etc, there are a couple of received emails in there that hold a very strong emotional value for me and I just can't get how such a thing can happen!