Syncing your Evernote files to both your PC and Evernote's servers may give you a feeling of security, but remember: Syncing is not the same as a backup system. Despite Evernote's safeguards, there's always the chance a human error, technological failure or act of nature could leave you without critical files when you need them. To truly secure your data, you need to perform a proper backup.
There are a couple of ways you can back up your notes, one using Evernote itself, and one using a third-party backup tool. We'll look at each in turn.
Backing up your notes
The first way to back up your notes is to routinely export them into an Evernote archive, which you can store on an external drive or in the cloud. From the desktop version of Evernote, just right-click on any note or notebook and select Export Note(s). You'll be presented with a dialog box listing several export formats. Select Export as a file in ENEX format, then name the file and select a directory. Note that if you export multiple notes, they'll all be consolidated into a single file.
Though this method is pretty straightforward, the downside is it must be performed manually, so it's best used when you just want to back up certain notes or notebooks.
To back up your entire Evernote database, you'll need to use either Windows' native backup tool or a third-party application like BackBlaze or CrashPlan. Make sure the C:\Users\[PC Name]\AppData\Local\Evernote\Evernote\Databases directory is included in your backups. Note, though, that with this method you must restore the entire database, even if you want to recover just one note.
Restoring your notes from backup
Regardless of which method you use to back up your Evernote data, before you restore your notes you must disable your PC's Internet connection to prevent Evernote from syncing during the process.
If you performed a traditional backup of your entire Evernote database, overwrite the C:\Users\[PC Name]\AppData\Local\Evernote\Evernote\Databases directory on your PC with the same directory from your backup. Right-click Notebooks within that directory and export all the notes to an .enex file.
From this point on, restoration is the same for either backup method.
In the desktop version of Evernote, go to File > Import Notes from Archive and select the .enex file you want to restore. Evernote will import all the notes in that archive into a new local notebook called [Archive Name] Import. For example, if you named your archive "Marketing," it will be imported as Marketing Import. Once the import is complete, Evernote will ask if you'd like to sync the notebook. Click No.
To complete the restoration, open the imported notebook and drag each file back to its original location in Evernote, then delete the imported notebook. Click Sync to synchronize your recovered notes.
Whichever way you choose to back up your notes, you'll have the peace of mind of knowing they'll be ready for you wherever you need them.