I read that a long time ago, don't remember many details. It was a short story written in English. About a city where clocks were forbidden. Workers in the city have wristbands with different colours to indicate their turns (say orange=morning, blue=afternoon, etc). Lectures at schools would start and end at the ring of a bell. Nobody have watches or clocks of any kind. This was the way of living there, this generation simply never heard nor need a clock. This boy starts to wondering about this, something mysterious had happened... Has anyone read it?
This must surely be Chronopolis, one of J.G. Ballard's early short stories, first published in 1963.
The story deals with a boy called Conrad Newman who lives in a city where clocks and watches are forbidden. At school, for example, the ends of lessons are given by the sound of a timer. He finds an old watch in his mother's jewelry box, and gradually becomes obsessed with finding out what had happened.
A teacher notices Conrad's watch, and takes him to the old "Time City", Chronopolis. There he sees the old ruined timepieces that completely regulated the society. His teacher explains the system to him. Different social ranks of people had their lives regulated by clocks of different colors:
"There were a dozen socioeconomic categories: blue for executives, gold for professional classes, yellow for military and government officials— incidentally, it's odd your parents ever got hold of that wristwatch, none of your family ever worked for the government— green for manual workers and so on.
"Let's say, for example, that a lower-grade executive leaving his office at the allotted time, twelve o'clock, wants to have lunch, change a library book, buy some aspirin, and telephone his wife. Like all executives, his identity zone is blue. He takes out his schedule for the week, or looks down the blue-time columns in the newspaper, and notes that his lunch period for that day is twelve-fifteen to twelve-thirty. He has fifteen minutes to kill. Right, he then checks the library. Time code for today is given as three, that's the third hand on the clock. He looks at the nearest blue clock, the third hand says thirty-seven minutes past— he has twenty-three minutes, ample time, to reach the library.
Eventually society revolted against this oppression. The Master Clock was dynamited, clocks had their works removed, and the Time Police were instituted to prevent citizens owning or constructing any timepieces.
Conrad ends up being arrested, but fights the system by constructing a crude sundial in his jail cell to measure the passage of time.
The text is freely available from the Internet Archive.