How can I get my iCloud back

If you forgot the ID, see if you can recover the ID. Use every email address you can think of.

Apple ID - How to find your Apple  -  An iCloud e-mail address is an Apple ID.

Apple ID - Find  -     

Other ways to find your Apple ID

You can check if you're signed in to the App Store, FaceTime, or Messages on your iPhone, iPad, iPod touch, or Mac, or check if you're signed in to iTunes for Windows on a PC. You can also go to iCloud.com or appleid.apple.com and see if your Apple ID prefills on the sign-in screen.   

If you forgot your Apple ID password

See this guide:

If you forgot your Apple ID password - Apple Support

Good luck!