How to find your serial number: https://support.apple.com/en-us/HT204073
If your device does not turn on, you will need the receipt from the Apple Store (search by the name of the store on your email, usually the subject line will be something like "Your receipt from Apple [name of the store]).
If you still have the box, your serial number is also there.
If you don't have your device
There are several places to check that might show the serial or IMEI/MEID number.
- Go to appleid.apple.com in a web browser on your computer.
- Sign in with the Apple ID that you use on your device.
- Scroll down to the Devices section. To see the serial and IMEI/MEID number, select the device.
If you still need help, here's what to try next:
- Do you have a different device with iOS 10.3 or later that's
- signed in to your Apple ID? On that device, go to Settings > [Your
- name]. Scroll down to see any devices signed in with your Apple ID. To
- view the serial and IMEI/MEID number, tap the device name.
- Do you still have your device's original package? Find the serial number and IMEI/MEID on the barcode.
Hope this helps,
Vicko