There’s not much in a fridge, a thermostat, a compressor and a light usually. I’m assuming that normal temperature setting (stat) adjustments don’t fix the problem.
If the light doesn’t work, check the fuse and / or change the bulb,
If the fridge is too cold even when the stat is adjusted warmer, the stat is faulty and needs changing.
If the fridge is too hot but the compressor runs and the fridge gets cold when the stat is turned right down, the stat is probably faulty.
If the light works but the compressor never runs regardless of stat setting it could be the stat, or possibly the compressor. The former is cheap. The latter not so.