Open Settings
Tap General
Tap Keyboard
Tap Keyboards
Tap Add New Keyboard
Select Emoji
Open any app with a text field
Tap the keyboard switch icon or globe icon
Choose Emoji keyboard
Press the keyboard backlight key, often marked with a light icon
Use the Fn key plus the backlight key if required
Press the backlight key repeatedly...
Open your device Settings
Go to General
Tap Transfer or Reset iPhone
Tap Reset
Tap Reset Keyboard Dictionary
Enter your passcode if prompted
Confirm the reset
Open Settings
Go to System
Tap Languages...