I'm not really sure what you mean. There are some animals in the book who are portrayed as being on the Witch's side and some as being on Aslan's side. The only character who is portrayed as changing loyalties is Edmund.

I believe in the second-to-last chapter they list some animals who are on Aslan's side. You can look there if you like. Actually, I'd recommend reading the whole book. It's great.

I mean after defeating the Witch, the evil disappeared and if all the animals that had helped the Witch as darfs or other animals changed their minds.

another question is it possible to know whay some animals talk? i´m reading the magician's nephew and I read that some animals where created with the talk skills. is there any reason?

Here's the relevant quote you want.

"At first much of (the main characters') time was spent in seeking out the remnants of the White Witch's army and destroying them and indeed for a long time there would be news of evil things lurking in the wilder parts of the forest-a haunting here and a killing there, a glimpse of a werewolf one month and a rumor of a hag the next. But in the end all that foul brood was stamped out."

It looks like everyone still alive changed to Aslan's side, or else hid away somewhere. The last chapter talks about things that the Kings and Queens did during their reign, and it does giv
[edit: thanks, Col Klink, you got there fast]

In The Magician's Nephew, none of the animals were created speaking, but then Aslan chose some of them to be talking, thinking, caring beasts. He told them to take care of the dumb ones. The reason is that it was part of what Aslan was creating - just like in our world, the creation story in Genesis tells that people were created separately and different, "in God's own image", to be in charge of the world and take care of the animals.