Forgotten Icloud username and password?
First, try and login to icloud.com and verify that you have your contacts and all the information you need there.

If you dont remember your password but still have access to your email you can try by using Apples iforgot page:
https://iforgot.apple.com/password/verify/appleid

You can try several different emails until you know your login, if you still have access to your email that is.

If you dont have access to your email, Apple can change that when giving their support a call, be prepared to answer a lot of questions amongst your security questions and for the last digits in your credit card number.