A refrigerator that has gone silent is easy to diagnose: no power. The harder complaint is the LG that sounds alive, with the compressor running and the lights on, while the milk warms. The causes span from a setting to a failed compressor, and the line between what an owner should touch and what is legally and physically off limits runs straight through the middle of that list.
Start With the Display
LG refrigerators have a display or demo mode intended for showrooms, in which the lights and display work and the cooling is switched off. On many models it shows as OF F or OFF on the panel, and it can be entered by holding a button combination for a few seconds, which happens by accident during cleaning. The manual for your model gives the combination to exit it. Then check the set temperatures have not been nudged; LG's recommended settings are 37°F for the refrigerator and 0°F for the freezer.
Airflow Inside and Outside
Cold air moves from the freezer to the fresh-food compartment through vents, and a compartment packed to the walls or a bag pushed against a vent starves the other side. Leave a hand's width of space around the vents. Outside the cabinet, the condenser coil and its fan need room air; the grille at the bottom front should be clear of dust, and the space behind and above the refrigerator should not be sealed off by a cabinet cornice or a stack of boxes.
Cleaning the Condenser
On most LG models the condenser and its fan sit at the back, low down, behind a removable cover. Unplug the refrigerator before you touch that cover, because the fan starts on its own and the compressor terminals sit beside it. If the refrigerator has to come forward to reach the cover, close the ice maker's water supply valve first so the line is not pulled off, and move the cabinet with a second person and a gentle roll on its wheels rather than a drag. Brush and vacuum dust from the coil and the fan, refit the cover, roll the cabinet back without kinking the water line and restore power.
Watch for the Signs That Say Sealed System
If the coils are clean, the vents are clear, the settings are right and the compressor runs continuously without the cabinet reaching temperature, or if the compressor starts and stops in short bursts, or if the freezer is cold at one end of the evaporator and frost-free at the other, the fault is likely to lie in the sealed refrigeration circuit: the compressor, its inverter drive, or a leak or restriction in the refrigerant lines.
Why That Is Not an Owner Job
Federal law under Section 608 of the Clean Air Act restricts anyone without EPA certification from opening a refrigerant circuit, recovering refrigerant or charging it, and that applies to a household refrigerator as much as to a rooftop chiller. The circuit is also under pressure, and the refrigerant causes cold burns on skin and displaces air in a small room. There is no valve to top up, no filter to change and no adjustment to make; the only correct actions are certified diagnosis and repair or a decision to replace the appliance. Do not remove the compressor cover, do not disconnect wires at the compressor and do not buy a refrigerant kit.
Meanwhile, the Food
Put a thermometer in the fresh-food compartment. The FDA's rule of thumb is two hours above 40°F, after which perishables go, and appearance and smell are not a test. Move perishables to a cooler with ice packs if the reading is above that line, and book an LG refrigerator repair with the model number, the compressor behaviour you observed, and how long the cooling has been fading.