i lost my little sisters minecraft account. no accsess.

Hmmm. It's possible you missed one somewhere else, then. When I played BioShock the first time, I accidently triggered the Extra Little Sister Bug in Neptune's Bounty and spent hours trying to find out where the mysterious 4th LIttle Sister went to. Eventually,
I gave up and went on, and I got the achievement regardless. If you have a save back in Point Prometheus (before you go to the Testing Grounds leading to Fontaine), I'd recommend backtracking with the Rapture Metro to the other levels and see if you left one
in an earlier place. If not, if have an earlier save in Fort Frolic or Arcadia, you'd have to play the game going forward from there.



EDIT: Your profile says that you've gotten the achievement already, though, so feel free to ignore the above.

I just started playing so I'm sorry I can't help. I'm still in Arcadia.

There are only 3 Little Sisters in Fort Frolic. if you've somehow managed to get 3/4, then you've triggered the Little Sister Bug. If she's already gone in the wall, she's not coming back out. Details are here

http://bioshock.wikia.com/wiki/Extra_Little_Sister_Bug. Don't worry about it. If you've found 3 of them, you're good to go.

I did get the achivement but it did not show up on the screen at the end of the game.

Thanks for helping everyone.