Proline fridge freezer - light on but nothing works?

Have an upright Proline fridge freezer (fridge at top) bought last year. Recently from working well both the freezer and the fridge have stopped working. The internal light works, plug and feed are fine but no noise or cold from either compartment. Any ideas how to establish what is wrong specifically? Have seen advice listing about five different possibilities ranging from new thermostat to compressor may be needed but no advice as to how to establish what specifically is wrong. If it is thermostat I could fix, if compressor I would recycle the appliance. can you help?