Are there any examples in history of countries returning to "lower" forms of government other than through conquest by...

Are there any examples in history of countries returning to "lower" forms of government other than through conquest by a foreign power?

Are there any countries that brought back their nobles after abolishing them? Countries where Kings were established where republicanism was one vibrant?

So far only France comes to mind what with Napolean (I consider the return of the King following Napolean to basically be a conquest forced by the rest of Europe)

Pre-colonial Mississippian culture.

Rome comes to mind.

Spain too. But in this case the monarchy brought democracy back

The UK going from monarchy to constitutional "monarchy"/parliamentary republic

Poland

If viewed from a Marxist perspective, going from USSR to Russian Federation was a step down since you're going from socialism to capitalism

Albania went back to a monarchy in 1928 after over a decade as a republic, only to return again after WWII

Happens all the time, Athens and Rome would always be changing between more and less democratic societies with the temporary Oligarchies and Dictators. France went back and forth for a while too after the revolution. In areas like Africa where things are always changing it happens fairly often as well.

This.

UK is still absolute monarchy. King can decline any act of Parliament and any offered stuff of Cabinet.

No it absolutely is not. It's a constitutional monarchy

Without constitution.

without a *written constitution

Japan.

Started life as a centralized empire with a de-facto-ruling Emperor with a meritocratic bureaucracy just like China and Korea. BTFO themselves by the central government doing nothing but art & being complacent, the social climbing and one upsmanship of noble houses related to the Emperor's household, and empowering the warrior class, sending them back into feudalism and strongmanship rule.

Sweden's age of liberty during the 1700s

State based on written laws. No constitution - no constitutional monarchy.

The Netherlands did

The english brought the monarchy back after cromwell died

The laws are written, just not on a single piece of paper at one time.

Germany went from Empire to Republic to Totalitarian.

Wasn't the emperor always a puppet for strongmen, the number of truly active/powerful emperors in Japan's history able to be counted on one hand?

I guess it depends on how literally you take Japanese history. Japan didn't even have a written language until the 5th century and didn't have a written account of its history until the early 8th century, so the accuracy of their record before then is debatable. Contemporary Chinese texts don't match with Japanese accounts.

Before the shoguns took over in the 12th century, actual rule was mostly done by either regents or retired emperors. So, I guess, if you consider a retired emperor an emperor, they ruled for a few hundred years.