Press and hold the "LOCK" or padlock button on the control panel for five seconds and try the temperature controls again. Refrigerator manufacturers often include a "LOCK" function to prevent accidental changes to the temperature settings.
Wait 24 hours after changing the temperature settings. Temperature changes take several hours to take effect in most models of refrigerator. Always allow enough time for a new temperature to be achieved.
Verify cooling mode is active by consulting your refrigerator's instruction manual. Some refrigerators can be temporarily disabled via the control panel without cutting the power supply. You may need to press and hold a combination of buttons on your control panel to re-activate its cooling mode.