There have been a number of revolutions that have happened since 1938. Some of these have been political revolutions. Others have been revolutions in the way people live. I am not sure which type of revolution you are asking about so I will discuss some of each.
On the political side, there have been many revolutions. Let us look at some that have really changed their countries fundamentally. These include the revolution that brought the Chinese communists to power, the one that brought the Vietnamese communists to power, the Cuban Revolution, the Iranian Revolution, and the revolutions in Tunisia and Libya. As you can see, the first three of these were all revolutions that brought communists to power. They all occurred in the Cold War era. The Chinese and the Cubans overthrew indigenous governments while the Vietnamese defeated their French colonial rulers. The more recent revolutions have been somewhat more religious in nature. All of them were, at least in part, fought by Muslim rebels who wanted more freedom than their autocratic governments gave them.
Outside of politics, there have also been important revolutions. Let us look at two of these. One was the “green revolution.” This was a revolution in agriculture in the developing world. Scientists developed new varieties of staple crops like rice that would be more productive. This enhanced the amount of food farmers could grow in these countries and greatly reduced hunger. More recently, we have seen a revolution in communications with the rise of the internet. This has helped lead to the globalization of the economy. The globalization of the economy has changed life in places like China where huge numbers of people have come to be better-off than they once were.
All of these, then, are revolutions of various sorts that have occurred in the past 75 years.