Lost folders in group library
I opened up my group library and the folder for organizing my files are all gone. The articles are all there, just not organized in the folders we made previously. The group members have not modified it at all.
Upgrade Storage
If you don't see what you're looking for in the trash, and this just happened, you or another group member may be able to restore them from the last automatic backup. Note the specific steps for restoring deleted collections.
If you're a group admin and you email support@zotero.org with details, we can tell you who made these changes.