I have played both Witcher 1 and 2, but I must have terrible memory since I'm a bit confused about some things in The Witcher 3

1. Ciri, where did she come from? I can't remember seeing or hearing about her in the previous games

2. Ummm, wasn't Yennefer supposedly taken by the wild hunt? Why is she just suddenly back? Or was that someone else?

Ciri is in the books and for whatever reason not mentioned much in the games. There are summaries else where that delve deep into books if you want but being at work and typing on a phone it's a bit too long to describe. Basically she was payment but Geralt refused as she was a girl and not a boy who could be turned into a Witcher if I remember correctly. They are tied together by destiny as well. As for your second question I actually don't remember.

Yennefer was taken by the wild hunt. Geralt teamed up with Letho and the other witchers from the Viper school and slaughtered a bunch of the Wild Hunt and they ended up in a stalemate. Geralt traded his soul to the Wild Hunt in return for having Yennefer brought back. It was in the last comic cutscene right before the final fight with Letho.

Well, that just proves my memory is really bad, cause I dd not remember that cutscene at all.

Geralt lost his memory the first two games so this is the first time she has been introduced in the games. Unless it was hidden behind some book or text i'm not sure.

@oursin_360: there are hundreds of hints about ciri and Yennefer in the first games but its really well done. Since Geralt doesnt remember they all just fly over his head and if the player hasnt already played the games or read the books it flys over his head aswell.

It can be a peasent telling a legend about a lady called cennifer "or something like that he cant really remember". Or characters Geralt met in the books that says some stuff Geralt cant remember and relate to.

Often Geralt answears something along the line "whata dumb story" ;)

I think I remember in the first Witcher where Geralt and Triss had a conversation about raising a child and Ciri might've been mentioned. That or they were just talking about Alvin.