First things first, switch the fridge freezer off at the mains.
Remove all contents and leave to defrost if necessary.. Do not turn the unit back on.
Remove the dead bulb from its socket. Removal should involve a simple 'twist and turn' process, similar to the one used to take out a normal lightbulb from a desk lamp or ceiling fitting.
First, apply gentle pressure to the plastic covering across the centre of the bulb, and then, while still pressing downwards, twist the bulb anti-clockwise until it begins to come away from the socket.
Look at the bulb closely to find which type of bulb it is and what power voltage it uses. You will need these details for when you purchase a replacement.
If you have trouble finding the correct bulb, try PartsMaster online. This website sells spare parts for thousands of electrical goods, including replacement bulbs for fridge freezers. Simply choose the manufacturer of your fridge freezer from the list provided, and then enter the model number and the serial numbers of the parts needed.
Before replacing the bulb, give the fridge unit a wipe all over with antibacterial spray. Dry completely before proceeding.
Now insert the replacement bulb. Once you have fitted the bulb, place two fingers over the plastic covering of the bulb, and twist it in a clockwise direction until it fits securely into place. Reconnect to the mains and check that the bulb illuminates.
Before replacing the contents of your fridge freezer, be aware that the temperature of your fridge freezer may take up to 24 hours to reach optimum temperature again.