My iPhone 7 or 8 cannot be located and someone has used it to possibly hack my phone and stole all my photos and personal information

How do you locate an shut down a previously owned iPhone 7 or 8 that does not show up on 'find my iPhone' and does not come up under my devices and cannot be located by any Apple apps or iCloud programs and the person keeps hacking my iCloud accounts (i have created several iCloud usernames and even had to create several new emails (as those were hacked too), as well as, all my social media apps and pretty much all the apps on my iPhone - they were all hacked and kicked me out everything and even my own Apple ID on my current phone!). They even managed to takeover my phone number somehow and shutoff my network service so that i couldn't make any phone calls. They pretty much broke 2 of my Apple XR phones within 6 months and ruined my computer too, as they hacked it through my phone some how. PLEASE HELP ME. NO ONE HAS BEEN ABLE TO HELP ME! I changed my phone number and sim card when i got my latest iPhone. I just found out they have gained access to my phone AGAIN!!!!! I do not know what to do!!!!!!!!!