Help!!

Can anyone tell me why my update page is no longer backing up what I write? 
I just wrote an entire chapter of the E-verse, and it didn't back up, at all. For some reason, when I hit backspace to take out an error, it took me to a previous page, and bam, whole chapter gone.
If anyone knows how to turn the backup function back on, now is a really good time to tell me, before I go off and cry.