If the file was deliberately deleted (sent to the Recycle Bin or Trash), the solution is trivial: open the bin. However, savvy designers know that Shift+Delete (Windows) or Cmd+Delete (macOS) bypasses this safety net. Furthermore, if you have emptied the bin, you have merely told the system to mark the addresses of all those books as available. This is where recovery software enters the stage as the digital equivalent of a forensic detective.
Use Adobe Creative Cloud Libraries or save your files to cloud-synced folders (Dropbox, Google Drive, OneDrive). recover deleted illustrator file