How Did Geralt Get Amnesia?

In CD Projekt Red's second Witcher game, Geralt recovers some crucial memories lost to to amnesia before the events of the first game. He remembers how he and his former lover, the sorceress Yennefer, were nearly killed by an angry mob while defending non-humans.

Is Geralt amnesia in the books?

But some of them are not even told the same in the books, the show, and the game Witcher III: Wild Hunt. Geralt's amnesia is one of those stories. So how did Geralt lose his memory? It was never really explained as a full scenario, but during the Witcher II: Assassins of Kings it is revealed he was almost killed.

How did Geralt get the scars on his back?

The White Wolf has the scars to prove it. Geralt has been caught in one (if not many more) race riots, he's been held prisoner in the dungeons of La Valette Castle, held captive and tortured by disgruntled Elves, and he's a professional monster slayer.