I have a steam account, but forgot about it for a while now.
This thread reminded me that I have some new games to play (If I ever get some free time).
Does anyone know how to look up my steam account name?
I don't even remember the email address I used and my credit card has since been reissued, so I don't have the original numbers from the credit card either.
If you don't know the username you used you're stuck unless you can find the e-mail that they sent you after they received your payment. It won't have the password in it but it will at least have the username.
You going to have to install Steam (if you don't already have it) and try guessing your username and password.