It's a girl and her little sister died a few days before then it's a bunch who want little sister's diary when they go to a mental hospital to lock all the doors, it is only 2 to survive in the movie

Please can someone tell me what this movie calls it's a girl and her little sister died a few days before then it's a bunch who want little sister's diary when they go to a mental hospital to lock all the doors, it is only 2 to survive in the movie

Your post is kind of unclear, but if you are looking for a movie where a girl is put into a mental institution after her younger sisters death, and only two 'survive' then you might be looking for this:
http://en.wikipedia.org/wiki/Sucker_Punch_(film)
(don't know about the diary, but I know the girls in the institution were collecting other things... )