How did Mr. Lamb's conversation and company change Derry's desire to isolate himself from the world?

Derry no longer care about his burnt / scarred face / his disability is no longer important

In the end Derry tells his mother that he doesn't care about what people say about his face anymore.

wanted to go back to Lamb's garden and feels if he did not go back, he would never go anywhere into the world again / ready to face the world

clearly shows that Lamb influenced him

became expressive/ confident / positive