I'd guess that routine-building might help. (Having no idea what you've tried so far.) Backpack always goes ____. First thing when she gets home is to write any long-term assignments on the calendar. Daily assignment book where she writes all assignments for all classes. Or, one binder with dividers for notes for all classes.
The hardest part of organization is building the habits. Any habit that helps her be more "together" will help.
Homework/Organization
The hardest part of organization is building the habits. Any habit that helps her be more "together" will help.