Q: Activate

Have you purchased second hand device or you are the original owner of this device?

If you purchased second hand device you need to contact the seller and ask him to remove this iPhone from his list of devices. Otherwise, your iPhone will be a useless brick.

Find My iPhone Activation Lock: Removing a device from a previous owner’s account - Apple Support

Also check these articles and follow the instructions.

If you forgot your Apple ID  - Apple Support

If you forgot your Apple ID password  - Apple Support

https://iforgot.apple.com/appleid

i am the original owner

Check aforementioned link if you do not remember your id. Good luck.

whats "aforementioned" link?????

If you forgot your Apple ID  - Apple Support

If you forgot your Apple ID password  - Apple Support

https://iforgot.apple.com/appleid

Contact Apple and ask for help.

https://www.apple.com/support/iphone/contact