Watch the video below which demonstrates how to:
Yes, most definitely. The online library can serve as a backup, providing it has all of the references updated. An example would be a computer hard drive failure. A new library can be synced and references brought it to it. Please note that if you have accidentally deleted some references from the desktop Library, they could also be deleted from the online library.
See how to backup safely in the next section of this guide.
If you have problems seek help from your librarian straight away, as they may be able to recover your references. If they cannot help, Crandon in Australia or EndNote technical support in USA often can.