she may have just eaten all the babies. my 2nd batch of fry all disappeared when i separated the male from the female. (the male seemed to be beating up the female and maybe for a good reason?) well anyhow the fry all disappeared. also... depending on the size of your tank that could have an effect on their actions.
As for your female dying.. i'm not sure how i'd revive her from the upside down swimming part.. but from my own experience they are hard to pair up again with another female, if it's even possible to do. good luck.