From House Digest https://www.housedigest.com/639015/genius-tips-for-getting-rid-of-washing-machine-smells/

Laundry Day happens to be the most popular chore day of the week. Right? That may be a slight exaggeration, but imagine opening the lid of your washer, and whew! There's an awful scent that you don't recognize. So how can you get rid of those stinky washing machine smells? Or worse yet, what would cause those odors in the first place?

You're in luck because we have some tips to share with you about ... well ... washing out your washer, especially if it needs a good, deep cleaning. Additionally, we'll share some maintenance hacks for a daily or weekly tidying-up that'll take just a few minutes, as noted by Better Homes & Gardens. For this task, you will need the following items: an old toothbrush, pipe cleaners, cotton swabs, washcloths, bleach, Borax, white vinegar, baking soda, some lemons, and your owner's manual in case you can't locate dispensers and other parts right away.