WLWBackup is a backup utility for Windows Live Writer for taking backup of Windows Live Writer. This includes blog settings, posts and plug-in. To run WLWBackup on your computer is that you must have installed .Net Framework 3.5 SP1.
How to Take Windows Live Writer Backup
open WLWBackup

Choose what you want to backup (posts, settings, plug-in, etc), and then click the Backup button

Once you’ve set the backup filename, let the program do its thing

How to Restore form the backup file
Simply double click on the backup file and You will be asked the same question about whether you’re sure you wish to restore

Download Windows Live Writer Backup Release Candidate