Were you able to find a solution?

At that age it is probably the last thing she is concerned about,l would sit down and have a face to face about how it’s bothering you.

Usually depriving children of what they value (like video games, tv etc) will make them do their chores. Find out what your daughter values and tell her she will lose those items/privileges if she doesn’t clean her room. Not sure if that will work with a 19 year old, but maybe worth a try.

In the book 123 Magic one suggestion is the ‘docking system’. I tried it once it and it was fabulous… had to stop as we don’t normally give our kids pocket money.
Basically your child pays you for jobs you do for them. So if your daughter receives $20 pocket money a week, and you have both agreed that she has to keep clothes of the floor, vacuum and make her bed – if she doesn’t do these things and you end up doing it, then she has to pay you, or you dock the amount off her pocket money. e.g. 50c for each item of clothing, $5 for vacuuming.

I have just finished reading The Life‑Changing Magic of Tidying Up: The Japanese Art of Decluttering by Marie Kondo. Seriously, worth the read. It’s a really interesting approach to why people find it difficult to maintain a tidy environment and why. I know this book has already made me look differently at how I tidy up and I consider myself to actually like tidying! Perhaps you could read it and then discuss it with your teenager. Or better still, get them to read it too.

if you can resist going inthere or doing herwashing she may get the answer there! I had twosons who with their respective partners now are wizzes round the home but I would pick up not now! all the best if you can be firm, another idea give surprise partyfor her friends let her know it is to be in her room!

At 19 it might be too late to start. (you are so lucky that going into her space hasn’t alienated her! ). She just might not see a tidy room as important, and/or be able to find what she needs and function as it is. But if there is a hygiene issue (eg dirty plates and food attracting insects etc.) or the floor can’t be vacuumed once a week to remove dust etc. that might be something that you can bring to her attention and explain that even if she can function in the mess that there is a bigger issue at stake for the house,and she needs to clean it. Then perhaps just close the door (and you are lucky if the mess is confined just to her space) and expect to be shown the room / floor cleaned once a week to prevent costly bills for removing house pests that are attracted to mess. Perhaps she would like the option of paying for a cleaner if she wont do it herself.