For three days, the narrator is totally out of it – or more out of it than usual. Some strangers take him in and care for him. Apparently they found him wandering around, singing, "The last man left alive! Hurrah! The last man left alive!" (2.9.2), which is currently tearing up the charts at the iTunes store.
While the narrator was out of it (for three days), everyone around the world heard the good news about the destruction of the Martians and sent a lot of food and supplies to England.
When the narrator becomes more lucid, the people caring for him tell him that Leatherhead was destroyed by a Martian "as a boy might crush an anthill, in the mere wantonness of power" (2.9.3). So much for finding his wife.
The narrator decides to go back to see what's left of his old life; on his way, he witnesses the England being put back into order, though it's still a mess. For instance, he finds a newspaper (which is a pretty normal thing), but except for a little news, the newspaper is mostly ads (which is… well, we're supposed to think that's strange).
To get back home, the narrator takes a train out, and he sees that all sorts of people are working together to fix the tracks. It makes us smile to think that people would work together.
When the narrator gets home, his house still looks abandoned. In his study, he finds an essay he was writing about what the morals of the future might be like. He never finished it because he was interrupted by the Martian invasion and now he can't imagine how he would finish such an essay on the future.
Then he hears people and he sees his wife. He rushes to her, just in time, too, since she faints.