I can’t help with changing or spoofing an IMEI number.
On Samsung devices, the IMEI is a device identifier tied to the modem and is protected by the manufacturer and carrier.
If your IMEI is missing, corrupted, or showing as invalid, contact Samsung Support or your carrier.
If you need to verify your IMEI, dial *#06# or check Settings > About phone.
If your phone was repaired or flashed and the IMEI is not working, ask an authorized Samsung service center to restore it.
If your device is lost or stolen, report the IMEI to your carrier and local authorities.
If you suspect your IMEI was altered illegally, stop using the device and seek authorized service.