If your freezer has stopped working entirely, check that it is plugged into the mains and there are no obvious problems with the wiring.
There are several elements you will then need to look into or call a professional to look at. Firstly, check if the freezer seal is working efficiently – you should be able to detect how strong it is when opening and closing the freezer door. If you’re unsure, put a piece of paper between the seal on the door and freezer and close it, try to pull the paper out and if it slides out easily, your seal will need replacing. Next, look at the temperature and make sure it’s set correctly.
For more complex checks, analyse the back of the freezer for ice or dust and debris covering the coils that normally allow for proper airflow and functioning. Give it a dust if you notice a lot of dirt has gathered as this could be clogging up the system. When ice is found covering the coils, you’ll need to call a professional for help.
If your freezer is covered with ice on every surface – to the extent that opening drawers is a struggle – it may be time to defrost the freezer. For other issues, it’s well worth getting an expert to take a look at the freezer thoroughly, which can prevent repeated faults.