For the last few days, I have had a sewage smell in laundry room. It seems to be coming from washer return house where hose goes into wall. I noticed it tonight, and we're not even using the washer. What can I do?

Is there a floor drain in the laundry room? If there is, and no water has been dumped down it for some time, the trap may have dried out and all you will need to do is dump a few cups of water down it.