At our LTC home, the clothes are sent to be washed, and then put on a cart to be redistributed by the night staff in the pt's rooms. Some of the staff weren't careful and didn't check the name tags, so some of the clothes ended up in other resident's rooms, never to be seen again (until a "careful" staff member would notice). The family members made so many complaints about missing clothes I got fed up, threatened to spot check the staff, and do some write up's.
Needless to say, this task is really simple, and requires almost no effort, so staff started to pay attention and everything went a little smoother from there. Also, I didn't have to write anyone up!
If you are in an Alzheimer unit, forget about it... Clothes and things will go missing... It WILL happen... A lot. We have a box full of stuff with about a dozen items of clothing and 10 pairs of glasses and have no idea who they belong to...lol
It sucks that stuff goes missing, but in your case, I guess you will have to backtrack and investigate to see where the problem stems from.