WD TV LIVE / WD MY BOOK ESSENTIAL: stopped recognizing HD

I recently deleted files on my HD to make room for media. These files seemed to be system files and folders… have no idea what they were, just figured didn’t need them… Well ever since I did that now my wd tv live doesn’t recognize my HD…anyone have ideas?

Is the my book recognized on the PC? You can try to backup the files in the my book and format it.