Hi, I'm looking for a movie,
It's about a women that kidnaps a girl (not sure how old she is).
I don't remember anything else but if you think about a movie it might be... don't hesitate to answer please... I do not remember that much... so it might be the correct answer!
Thank you verry much!

Down Will Come Baby (1999 TV movie)
Starring Meredith Baxter, Evan Rachel Wood
In this, a woman kidnaps the girl who was with her daughter when she drowned while at camp.

You can read a capsule description and reviews, which give more plot details, here:
Down Will Come Baby (TV Movie 1999) - IMDb

Locked Away (2010)
Starring Kirsten Prout
In this one, a high school senior seeks help from a pregnancy counselor, who exploits the situation for her own gain. She kidnaps the girl and places her in a "home" for other girls in the same situation.

You can read about the film here:
http://www.imdb.com/title/tt1639080/