Disappearing folders and functionality
I recently purchased a new Macbook pro, installed Zotero, and synced the library. Since doing so, two things have occurred. First, some of the folders in my library seem to have disappeared. Second, I can no longer "manage attachments" (this option has disappeared). I often save pdfs to the Zotero entry, highlight them, and extract the annotations. My extracted annotations are now gone and also the ability to highlight newly-downloaded pdfs. As I am in the middle of a book project for which I rely on Zotero, I am anxious to retrieve both the entries and the ability to manage the attachments.
zotfile.com/
For the collections, have you tried searching for items that were in those collections? It's quite hard (I think minimum 4 mouseclicks) to actually delete items in Zotero unless you want to do so, but it's comparatively easy (2 clicks) to delete a collection by accident.
For Managing the Attachments, thank you for reminding me about zotfile. I think (hope) that will restore the functionality. I forgot that this has to be installed separated.