Email address is already in use but can't find the apple id

Hi,

I'm trying to change my apple id email address.

When I'm doing so, I'm getting the message that this email address is already in use.

So I want to delete the account that is assigned to this email address.

But, When i'm trying to reset the password for this account, I'm getting the message that there is no apple id for this email address.

I'm going crazy, is there account on this email address or there isn't??

How can I find which account is using this email address?

Please help.

thanks.