For starters, huge swathes of land were utterly devastated from the fighting, many countries were divided up between the allies (i.e Germany, Korea).
Also, the Americans and Soviets began competing over which system was better (capitalism or communism?) which only furthered world tensions and damage. The war also left many economies devastated from putting so much into their militaries.
Many population centers were completely obliterated (70 - 80 million casualties in ww2). And in many countries new dictators and tyrants were able to take over and just make life worse for their already struggling people.
The spread of the Italian innovations and art was spraeding to Europe (THIS IS WHAT SET OFF THE NORTHERN RENAISSANCE, IT WAS LIKE A CONTAGIOUS DISEASE OF INNOVATION)
The cities of italy also grew and expanded in size and in power as well
