Lost phone forgotten online password

I lost my phone on the 15th since then a friend of mine gave me his phone. I went online to AT&t prepaid to log into my account, I.e the lost phone, and accidentally hit send temporary password. Now that I don't have this phone and number the temporary four digit PIN number was sent to the phone that is lost I don't know where it's at and I can't access any of my Gmail accounts because they're linked through the two-step verification process with phone number that's lost how do I get back into my prepaid account?