Help - my ssd is missing 40gb, after I tried to install Bootcamp

Here is the situation. A few weeks back I tried to install bootcamp and windows. It did not go well, but lets forget windows for the moment.

The problem is that I partitioned my Macbook Air's ssd, creating a new windows 40gb in size. The win install did not work, but now, I cannot recover the 40gb. In fact, it is invisible. I thought I could fix this myself, I waited for this weekend when I had the time. I superdupered a copy of my ssd to an external drive, and attempted to reformat the entire ssd, with the intent of copying the external drive contents back onto the ssd. It did not work.

Disk utility could not erase my ssd. The message was that there was a discrepancy with the drive size, and that was that.

I have no more ideas. Can anyone suggest how I can get my missing 40gb back?

Many thanks to anyone who can help.