WD My Book not backing up

I recently discovered that my My Book stopped to backup the files. It automatically updates every day and says everything is ok however when I’m clicking on the icon it says the last backup was made for few months ago. The recent files are not updated. Any ideas where to search and what to do are appreciated.

So I went ahead to trying figure out whats wrong with my hard drive. Apparently, its something with the backup part because my hard drive showing offline.

I went thru all steps described on the webpage and it’s still not working. I can see harddrive in my finder but in backup software its showing offline.

I erased my backup drive, I uninstalled backup software and installed again. Deleted the old backup plan and created a new one. Now I get an error message that the target is full. Still no answer from support or community. Worried.