SD card removed from an Arduino board and put in a pc Windows

Hi all, I am a newbie of Arduino, 63 years old…. I removed an SD card from an Arduino board Mega 2560: I put it in a pc windows in order to read the data in it stored. I managed to read the data. Then I put again the SD card in the Arduino board but unfortunately it cannot be read : the sketch CardInfo always gives me the error: Inizialization failed … Can anybody tell me if it is possible to solve the problem letting Arduino read again the SD card ? I specify I didn’ t change anything in the Arduino board either before or after removing the SD card. Thanks for the attention

Is your SD card slot part of an ethernet shield? The below has been posted in the forum for testing if the SD card is detected when used with an ethernet shield.

#include <SD.h>

void setup() {

  // disable w5100 SPI
  pinMode(10, OUTPUT);
  digitalWrite(10, HIGH);

  Serial.print(F("Starting SD.."));
  if(!SD.begin(4))  Serial.println(F("failed"));
  else Serial.println(F("ok"));

void loop() {