As your microwave gets older, it can start to smell, sometimes like something is burnt. Did you know why this happens? It is because over time the plastic that is inside starts to absorb food odors.
These odors can be taken care of with some simple cleaning steps. Take a microwavable bowl and add one cup of water, then add two tsps of baking soda. Then just place the bowl into your microwave and cook for three minutes. Doing this should absorb the odors, and it will also loosen dry food that may be inside.
If you have a plate inside your microwave take it out and clean it with hot soapy water. Also wipe the inside of the microwave with a soapy rag.
If you can not get the smell out, try mixing a 1/4 of bleach with one quart of water and wipe your microwave down with this mixture. Make sure to rinse the inside with a clean wet rag.
Mixing one part lemon juice to two parts water into a microwave bowl, and cooking for five minutes will also help with the odors.