Good morning, I am struggling to look up the part \ model number provided, can you please double check.
If the LCD display backlight is not lighting up, can you advise if pressing a button on the device makes the light come on?
When lightly pressing the display does the back light come one?
Good afternoon this is a hardware fault in the phone itself, it could be a lose connection or a failed backlight.
Unfortunately this isnt a setting which you can change to make the backlight come back on, the backlight should come on each time the key is pressed or a call is received, and turn off automatically after 15 seconds. The only setting you can change on the phone is the LCD contrast, which wouldnt help in this instance.
To this end the only suggestion I can make is you look to buy a replacement phone, you can purchase the same model from here for £51 including delivery.