Oh doesn't it suck when you lose it! Sorry I can't help either but, I posted the same thing a few months back. Ours ended up being on my bedside table it wasn't until I rearranged the bedroom that I saw it just sitting there. Ridiculous I can't believe it was there the whole time!
So have a look in some obvious places Although I'm sure you already have...maybe it went in the washing basket with some clothes after she got changed?