See if you can recover the ID/password.
Apple ID - How to find your Apple https://support.apple.com/en-us/HT201354 An iCloud e-mail address is an Apple ID.
Apple ID - Find https://iforgot.apple.com/appleid#!§ion=appleid
Enter the Apple (iCloud) ID and click Forgot Password.
Apple ID - Manage https://appleid.apple.com/#!&page=signin
Apple ID – Forgot Password https://support.apple.com/en-us/HT201487
If necessary, if you are the original owner, take the device, the original purchase receipt with the serial number, and a photo ID to the nearest Apple Store.
Genius Bar Reservation and Apple Support Options - Apple. https://www.apple.com/retail/geniusbar/
or contact Apple ID Support. They will need to see the original purchase receipt/paperwork also.
Apple ID - Official Apple Support. https://support.apple.com/apple-id
Contact Apple for help with Apple ID account security - Apple Support. https://support.apple.com/en-us/HT204169
Get Support https://getsupport.apple.com/. Work through the screens to get a chat option.
https://twitter.com/AppleSupport
Or fill out and submit iTunes Store - Contact Us - Official Apple Support https://support.apple.com/en-euro/itunes-contact The form is for iTunes, but it will get passed to the ID Support section.