Backing up your EndNote files is essential to securely save all your hard work.
Each EndNote Library contains two components - an .enl file plus.data folder- always back up both into same folder.
Backup your Library:
Compress or save a copy of your library to a removable disk (or another drive) for safekeeping.
If you elected to Create & Email the library, EndNote will launch your default email system, create a new email and attach the compressed file to the email.