Do not use bleach or harsh chemicals as these can make people ill, if they come into contact with food. Only use natural/environmentally friendly products.
Even a spray bottle with half vinegar and water will be good to use to clean the fridge.
Remember to remove all the shelves, containers, vegetables drawers so you can reach every nook.
Check all the food items for expiry dates and throw out if old and mouldy.
If there are any odours in the fridge, you can use a bowl with either baking soda or vanilla essence and some water.