I had a drop of roughly 800 or so pages yesterday, upon checking this morning it's gone up around 1000 so hopefully your does to.
Most people saw a drop, then have found they now have more pages indexed than before. I'm pretty sure your site will recover like everyone elses. This has been a positive update for many webmasters.
Pages indexed lost and returned, back links lost. It's all over the place. But while it was happneing the bot spend the entire time visiting. There's no rhyme or reason. Give it a day.
my pages went from 3000 to just 12 i think its to do with their index update, my rankings are still their so thats all that matters at the mo