My WD Elements portable hard drive wont back up my Windows 7 hard drive files

My WD elements portable hard drive which is 4 months old wont back up my windows 7 files any more (stopped about 2 months ago). I use the Windows ControlPanel/ Backup and Restore to initiate the backup as I have always done. The backup commences but just at the end it comes up with "The last backup did not complete successfully’. I’m at a loss. Can someone please shed some light on the problem?

This fact often confuses people.

Your Hard Drive isn’t backing up anything. It’s only STORING files. You say you’re using Windows Backup to do the backup, so the issue lies there.

We’ll need to some more info about what exact errors you’re seeing, or perhaps even look in your Windows system logs to see if there’s useful indications there.