I want to know in a Arduino project while it has been connected to many io peripherals, if any disconnections occurred with Arduino means how to detect it.
I assume that the IO peripherals you are talking about are nothing but sensors. If not correct me!
So you wanna know if your sensor is connected with your Arduino and is still functional right?
All sensors feed in a variable voltage of 0-5V for the Arduino. So simply add a pull down resistor of 10k to the Analog pin of your arduino. This should give a voltage of 0V to your arduino when the sensor is not connected, whenever the sensor is connected and functional it should give you a voltage of something above 0V.
You can simply check this using your arduino analogRead(); function and detect which sensor is malfunctioning