To fix and repair the device you may first try: Replace the LCD screen module just to easily confirm if the LED's on it is still working or not. If the it still shows a dark screen display, you may refer to the solution below and do have a check and test procedure on some components and connection line paths of the LCD display LED.
Nokia 2220s Display Light Jumper Ways
To fix the problem, you may first check the LED Driver supply voltage on the filter coil and check also the coil. If the there is a voltage reading on that component, check the 0 resistor below the LED Driver, replace it if found damaged.
If the resistor is okay, trace the negative and positive LED feed voltage line paths down to the LCD pin connector pin#21 and pin#22. Just manged to apply a jumper wire if found open or cut-off.
If the above procedure does not solved the problem, replace the LED Driver IC. IF this IC become faulty it will absolutely result to Nokia 2220 slide display light failure problem.