We recommend creating regular backups of your EndNote library and saving it in another location, preferably somewhere that is regularly backed up.
The File > Compressed library option, enables you to save a single backup file containing your references and any attachments.
Open your EndNote library.
EndNote will then create the compressed Library. This can take a few minutes, depending on the size of your Library and the number of attachments.

Saving Compressed library (.enlx) backups to a CSU network drive OR external hard drive will reduce the risk of the loss of your data. If you do need to revert to a backup of your library, we recommend copying the compressed Library to your computer before opening it.
When you open a compressed library, it will automatically expand to form a .enl file and corresponding .Data folder. After which you can delete the copy of the compressed .enlx file that you copied to your local hard disk.