If your Samsung Galaxy cannot detect your SIM card it could be down to a fault with the SIM card. Consider first speaking with your network operator, if you haven’t already, as they may be able to detect the problem at their end and may need to issue you a new SIM card.
Your Samsung Galaxy may be able to detect your SIM card once its software is up to date. To update your device’s software follow the steps below. Note: these steps are for recent Android devices, the exact steps for your Samsung Galaxy may vary slightly.
1. From the Home screen touch Settings.
2. Touch About device.
3. Touch Software update.
5. Touch Update.
If your device does not detect your SIM card after installing the latest update proceed to step 6.
6. Back up all the data you have stored in your device to a computer.
7. From the Home screen on your device touch Settings.
8. Touch Back up and reset.
9. Touch Factory data reset.
10. Touch Reset device (make sure you have backed up all the data you wish to save beforehand).