Is my storage memory destroyed?

[AC Question]

I recently tried to download a rather sizable app. The description said it would need 2.42 gb. I deleted pictures and uninstalled apps until I had about 2.63gb of space. Hit install and let it work. Even over wifi it took about 20 minutes. When it finished downloading eveything I got a "storage space running out" message and it did not install the new app. Now, when I go to the device memory, it me there is 16gb total space, between applications, downloads, etc, I am using about 10gb. But I only have 187kb of available space. Where did all my memory go?