My Book

I currently have over 4500 photographs saved to My Book .  Yesterday I could not gain access to my Book and a message kept popping up telling me the drive is unformatted and I need to format it.  I do not want to lose my 4500 photos which represent six months work and are very important to me.  What options do I have to gain access to my photos and fix this problem.  The drive is now full with no spare capacity.  Could this be part of my problem?

I would appreciate any advice I what to do next.

Look in Disk Management and see what it says about down where the bars are shown. There is a lot of recovery software around. This post has some links in it
If you’re thinking of professional data recovery it’s best to leave things alone.