A 9 year old can do her own laundry.
She might actually care more about it if she does.
Anything not in the hamper doesn't get washed. No exceptions.
When she doesn't have her favorite shirt, or whatever, hmmmmm. Where is it? Why didn't it get washed?
If she doesn't put her clothes away and has to search for them? Hmmmm. Wonder where they are.
If she doesn't like them wrinkled because she didn't put them away, the natural question would be.......how can she do something about it?
Let HER find the answer to that question.
Don't take this the wrong way, I have a daughter too, but quit buying her clothes.
She has so many that she doesn't care for them.....don't buy MORE.
You can, without even saying anything or threatening, make sure she has enough for one week. Shirts, pants, socks, underwear, pajamas.
One set of something to wear for each day, for one week. No multiple choices. YOU choose 7 shirts, 7 pants, seven pairs of socks, panties and jammies.
Take the rest out of her room. Make her wash her own laundry for that week and if she doesn't put it away, fine. She can wear the same week's worth of things the next week. Don't give her more clothes or a choice unless she washes and puts one week of things away at a time.
It might sound mean, but to be honest, I think sometimes our kids get overwhelmed by the amount of clothes we provide them.
They have so much they can go a long time without even knowing where things are or if they're clean. Then....we buy them more.
Clean out her closet and drawers. Anything that doesn't fit or she doesn't like, donate it. Give her a manageable amount to deal with herself.
One week's worth of clothes.
That's it.
If she doesn't like it, and she probably won't, tell her that at least you know, at worst, both of you only have to deal with 7 days worth of things. If she can't keep track of that, then maybe she can only have 4 days worth of things to wash, fold and put away at a time.
You don't have to put it to her as a "punishment". You're just trying to help her "manage" things. If she has too much to manage, then you are just trying to make it more simple.
My son is 15 and has been doing his own laundry for years. Nurses at work were talking just the other day about their sons helping with the laundry for the household.
If boys can do it, so can girls.
Don't think of cost efficiency, etc. Don't let her wash a shirt at a time.
Give her a manageable amount per week.
Also, give her laundry chores for the rest of the family.
If the washer is getting loaded and there is nothing of hers going in or coming out, that's up to her. She still has to help. After all her efforts sorting, washing and folding and putting away, if she has nothing of her own to wear, she has no one else to blame but herself.
Like I say, don't harp on it, but laundry is a part of life and she either makes sure hers is done with everyone elses or done by herself...or she has no plethera of clothes to find under her bed to wear.
So far, the clothes situation is bothering you more than her.
Until it bothers her more, it's going to stay that way.
Best wishes.