Yr 7 dd has lost/misplaced so many things

[Notsuretoday]

I'm at the end of my tether. She has also missed instrument lessons and been generally disorganised.

What on earth can I do to get her to improve? At home I check she has packed her bag etc, but while she's at school...

Aaaaaaaargh

We're finding the same. Have abandoned music lessons...dc's missed loads and when they did go it caused issues with the class time they missed....sadly it was all too much.
Pack bags the night before and every school belonging is placed in a large plastic container at home - so nothing gets left lying around.
For lost items that need replacing, we make them contribute financially, towards the replacement, usually 25%.