Combine 1 cup of water with 2 tablespoons of lemon juice. Bring it to a boil inside the microwave and keep the microwave on "High" for five minutes. Leave the bowl in the microwave for another five minutes before opening the door. Wipe down all interior surfaces.
If lemon juice fails to work, repeat the process, but add four or five cloves to the water. Or try using half of a chopped lemon, along with its pulp and rind, instead of lemon juice.
Scrub the interior of your microwave with 100 percent white vinegar. Leave the oven door open to let it evaporate on its own. After a couple of hours, wash it out with a mixture of dishwashing soap and water.
Leave a shallow bowl of baking soda in your microwave for a few hours or overnight. Also try combining it with vinegar to form a paste, and scrub down the inside of your microwave. If your microwave still smells bad, check to see if any food fell into or exploded into the vents.