Try sending a private message to GPG-Servo on this forum asking for help. He is a GPG employee and may be able to track down what user is attached to your key. However, he is very busy, so it may take a while for him to respond.
Another option is to try sending the info back to you using the e-mail registered to your account so that you can get the password, but I'm not sure if you can send a username back through e-mail.
You could also try to make a new account using the same key and e-mail address, then consolidate your accounts to the newer one.
Before doing any step other than PMing Servo, be sure to install the latest version of GPGNet and run it as an administrator. The latest version of GPGNet is here