I have one, called Like Father, Like Daughter. You should just sift through people galleries.

well,one of the fics i wrote was kinda sad.but i`ve read others...i just forgot there titles and authers`

I have a few sad ones (though they won't make a bit of sense if you skip over their prequels). Rotramel the Writer has several sad ones, which are some of the best I've read in a while. To find others, you've just got to ask around; people all over the site know all kinds of fanfics of different genres.