Find the Source

• Inspect the carpet for stains. If the carpet was subjected to large amounts of water, it may have mold or mildew in or underneath. Sometimes the padding, not the carpet itself, is the source of the odor. Pull up an area of the carpet and check the padding below. If the padding is the culprit, it will need to be replaced.
  
  In some cases, the carpet is simply old and needs a good cleaning. Perhaps a heavily trafficked area requires more frequent attention to prevent the smell. Once you locate either the source or the cause, you're on your way to banishng the smell.
  
  

Cleaning the Carpet:

• If you own a carpet cleaner, put it to work (you can rent carpet cleaners at most grocery stores). Push the furniture out of the way and keep everyone out of the room until the carpet dries. Open up the windows to air the room out and speed the drying process. A fan also helps the carpet dry more quickly.
  
  If a carpet cleaner isn't an option and you don't want to hire a professional, try this solution: Add a cup of white vinegar to a gallon of warm soapy water and gently scrub the carpet with a cloth or sponge. Be sure not to saturate the carpet as that will make it tougher to dry.
  
  

Quick Solutions

• Sprinkle baking soda all over the carpet and leave it for several hours or overnight If possible. The baking soda will help absorb the odor. Vacuum it up in the morning.
  
  Misting the carpet with white vinegar from a spray bottle can also help to eliminate odors. Ventilate the area well as vinegar doesn't have the most pleasant aroma. When it dissipates, the carpet will smell fresher.
  
  Cut up an onion, place it in a bowl of water and leave it in the middle of the room overnight to further absorb odors. For maximum effect, close off the room.