How can I fix my hotpoint frost free fridge with a code number of 76 34939?

The fridge can be plugged on for the whole day but its not freezing. The indicators in front of the fridge shows that the freezer temperature is high and it is not freezing. What might be the problem of the fridge and how can I fix it?
The fridge is a hotpoint frost free future with Microban code 76 34939 7600 S/N 507010188 Model FFA74P