If you don't remember your login info/have your old registration code, you might be SOL.
Speaking from experience. Have my disc and everything, character is on Lodestone, but I can't for the life of me remember my login/pw.
SE account recovery is pretty simple. I couldn't remember some of the stuff for my FFXI account so I had to contact them. I think all I needed was my name and a product code from either FFXI or any one of the expansion codes tied to my account.
You can go to their site and figure out how to contact their help, most likely through e-mail or call them and get it sorted out on the phone. If you can remember what e-mail is tied to the account then your life will be a lot easier. Edit: Derp, you pretty much said what I did already. That's what I get for skimming over all the posts at once. XD Edited, Jul 22nd 2013 5:59pm by DamienSScott
FFXI: DamienSlvrblade Race: Elvaan Nation: San d'Oria Server: Sylph 2002-2007, Phoenix 2012
PUP WHM PLD MNK BLU BST SAM WAR BLM 99 BRD THF NIN DNC SMN RDM 50+
FFXIV: Damien Scott Race: Duskwight Elezen GC: Limsa Lominsa Server: Ultros
DoW GLA50 ACN50 PUG50 MAR 50 Rest30+
DoH/DoL All 40+