Take everything out and wipe it down with a vinegar water solution. Dry and replace. I live by myself so easy to keep a clean fridge, but with families, not as easy!
This is what I do....I turn the refrigerator off (don't unplug it because you want the light to stay on so you can see). Take all food stuff out and then take all the crisper drawers out. Then I take the top shelf out and clean it and the refrigerator wall behind it, then reinstall. Then I take the second shelf out, clean it and refrigerator wall behind it and reinstall.....I do this to all shelves and crisper drawers. Then start on the inside of the door....take each shelf out and clean it and behind it and reinstall. When refrigerator is all clean, wipe down all the food and containers you are putting back in. When done, turn the refrigerator on and shut the door. Next I clean the outside (top, sides and front) Done! A reminder ...refrigerator may need to be pulled out now and then to clean the back of the unit. It is not an easy way to clean, maybe but probably the best for me, at least.
Would just like to add — now is a good time to get rid of dated condiments, salad dressings, gummy jellies/jams and dated or moldy cheeses and lunch meats. They are totally and easily replaceable.
Like Pat said , not an easy task , but if you can pull away from wall it's important to remove excess dust from coils on rear of fridge .
Once clean, put food safe shelf liner down. It’s pretty and practical.
Vinegar and water or baking soda and water. Both are earth friendly, economical, and food safe.
Store food in a cooler while you are cleaning the fridge. Take out and discard anything expired. Pull out drawers and wash in the sink - it’s so much easier than trying to clean them while they are still in the fridge. Hot water and a squirt of dish soap can work magic. The hot water loosens stuck on food. Wipe clean and put food back!
Ok I probably should have said :I had everything spoil after an extended power outage. It's REALLY NASTY inside the refrigerator and freezer.
Then you might also want to use a cleaner like Lysol (the spray-bottle cleaner) with Hydrogen Peroxide (comes together) to kill lingering germs/discourage mildew. Dry thoroughly before putting anything back in!