Your room has "acquired" a smell, and you can't seem to get rid of it. Things that are clean generally shouldn't smell, but some odors have a way of getting all over everything. This article explains several ways that can work to help remove odors in a room.
1. Open the window. Let fresh air and sunlight in. If it’s cold outside, try using a fan.
2. Take smelly items outside to air out in the sunshine. Bring them in at night. Do a sniff test. If one of the items is the cause of the odor, don't put it back in the room.
3. Check air vents and wall outlets for odor sources. A dead mouse in the wall will smell up the whole room, but will be most noticeable around a wall outlet. You will either have to wait months for that to go away or you'll have to remove part of the wall to get to the remains. You'll also have to seal the hole into the wall (likely in the attic) where the mouse entered.
4. Vacuum the room. This includes not only carpets, but also upholstery and curtains. Vacuuming also pulls dust and debris out of the carpets.
5. Wash hard surfaces. This includes glossy paint, hard flooring, walls (glossy/semigloss paint only), counter tops, sinks and tables.
6. Professionally clean the carpet. If you think the odor is in the carpet, or the carpet still harbors odors, clean the carpet professionally. If you know the odor was a specific spot on the carpet, you could also spot treat that area.
7.Wash clothing, bedding, and linens if they smell like whatever you are trying to remove. Hanging them outside to air dry might also help.. Don't forget throw rugs, blankets, and any other fabric items that have become a fixture in the room.
8. Have your upholstery professionally cleaned. For leather upholstery, wipe it down with oil soap or saddle soap made for leather.
9. Change the filters in any ventilation, heating, or air conditioning system. Those systems work better when the filters are regularly cleaned anyway, and if you're trying to get rid of odors, there's no sense having them circulate in your ventilation system. If you think the ventilation system is the source of the problem and changing the filters didn't help, see about getting your ducts cleaned.