I can't access my serial number, my ipad is locked

Dear Uzoi, the Model and Serial Number should be on the back of your iPad. The writing is very small and may be difficult to see but hopefully you will see it.

https://support.apple.com/en-au/HT204073

To find your device serial number, simply sign-in to your AppleID account from any web browser:

https://appleid.apple.com

Once signed-in, select the Devices tab from the main menu - where you will find the details of all devices.

Uzoi Said:

Serial Number:

Q1. "I can't access my serial number because my ipad is locked"

A1. Look on the original packaging.

Genius Bar Appointment:

Q2. "I need an appointment to visit your customer service center"

A2. Set one Up here: Genius Bar Reservation and Apple Support Options - Apple