the topic has been discussed in the movies and TV shows but if you really want to know, in short, they rebuild. the Netflix shows deal with the rebuild in NYC and how some shady folks even took advantage of that to gain some control over the city. they even deal with how the average person on the street is handling what's been going on and how some people feel about "heroes" now. Agents of SHIELD literally showed them cleaning up after some battles that happened. Civil War dealt with the consequences of The Avengers going around tearing things up fighting bad guys. Spider-Man dealt with Tony Stark creating a company called Damage Control that's been tasked with cleaning up after super-hero battles (that's also referenced on the TV show) and how that affects one guys business in particular. there was actually going to be a whole TV show called Damage Control that deals just with that group who clean up after the Avengers (or anyone else I assume) has a big battle that needs to be cleaned up. not sure if that show is still happening now or not.