Not all of my cards are downloaded from the shared deck file

during the first simester I made more than 15000 anatomy cards. all of them i shared with my class and i have uploaded on my Ipad and Iphone. A week ago i noticed that the cards disappeared from my decks\ account. i tried to restore it from the files i have on my devices but it only download 10% of the cards. (I already checked in the browser, the numbers are nit matching).
Help me what can I do, I have an anatomy test soon.

If you can locate them in an automatic backup, then you can export + import them into your current collection.