how about if you cant access to your account

hello I just got a new ipad that was a replacement for one that I took to the store because the display screen froze up on it, I ve been trying to recover the backup data within the icloud. My problem is that I can not recover my icloud backup. The password is not accessing. Around the end of February or early March my E-mail was compromised and I was unable to enter it anymore. I contacted Apple support and had my information changed ( E-mail user name and Password) then today the display froze. I contacted my local Genious support team and made an appointment. At the appointment the Genious Representitive changed out the defective Ipad for another. As we were attempting to Startup the new Ipad the login that I had changed it to would not work. I need to find out if there is any way to find or reset my cloud account.