Well, if you never open your windows, your house will not smell nice, that’s for sure.
Open windows every day. When I lived in England, even on the cold days, I would walk around our (teeny) house and open every window, count to ten then go and close them all. All the air got exchanged and it just felt fresh.
Your washing should be dried outside as much as possible and dried properly.
If a room is particularly funky, strip the bed and wash everything, get quilts, blankets, pillows and soft toys outside and stand your mattress up with the window open. The weather needs to be dry, not necessarily warm. Cold, clear weather will do just as well. If you think that’s not enough, open the wardrobe and drawers to air as well.
I regularly get our pillows and quilts outside, even the sheepskin mattress cover. Shake and bash. You will be horrified at the crud thwt flies out.
Work around the house, one room at a time and get it clean and fresh. By the end of summer, you won’t know yourself.