How can I get my password back in this way?

My friend changed my account password and he doesn't let me know it. So I went to Account Administration to get my password back(I marked on Lost Password), I'm really the first person that created that account, I am very sure that I filled in all correct account informations, such as Login Id , Current Register Email, Account Creation Date, IP Address. But, the supporter said, " Your account creation date is correct but all of the other information you have provided does not match our records".

HOW CAN I SOLVE THIS PROBLEM? Plz help me GM ! Thank you! Sorry for my english if it is hard to understand:(.