I'm in the same situation.
I went through a phase where i had to create new email addresses to create new accounts on PSN. That was many years ago and those e-mail addresses were used solely for the purpose of creating said PSN accounts. Well I finally stuck with one and just had it on auto-sign in for all these years and it was just never an issue. Sony never once required me to check that email address for anything except (maybe) when I first signed up...so I never did (why log into an email address if you don't need to check it for anything?).
Well fast forward to today where I just restored my system defaults on my PS3 to get mass effect 3 to work. The game worked, but it deleted the auto-fill in information when signing onto PSN. I have no idea what email address I used. I tried all the ones I could think of, but I know there's more that I simply cannot remember due to the fact I never had to use them for anything other than creating this account. So I figured I could call Sony Support, speak to an agent, and get them to help me figure out what email address I used. Afterall, I went through the same issue with my Wells Fargo online bank sign-in ID, my netflix logon ID (which was also an old email address I never used anymore), my credit card online log-in ID, etc...and they all helped me locate my login ID so I could recover my account. Not Sony...they said they could research what that email address is based on my displayed online ID, but that they could not give out that information. I called twice just to verify because I couldn't believe what I was hearing...my account is lost forever or until I somehow remember what that email address is.
So that's where I'm right now...I lost hundreds of dollars worth of DLC and all my hundreds and hundreds of hours spent racking up stats and climbing through tournament leagues in various games (mainly hot shots golf). The CSRs at Sony Support were very friendly, knowledgeable, and willing to help out. Unfortunately, they simply had no procedure to follow to help us out in this situation.
After researching this issue, it seems like it's the same scenario with everyone else who lost their accounts. People wanted a new online display name and thus had to create a new email address to create a new account. Since those email address' sole use was only to create the new PSN account thus leaving no reason to every sign into it again, people forgot what it was.
