1. SD CARD PROBLEM
Your Android device may stop recognizing your SD card or may not show the data inside it. Usually, this happens when the SD card is not inserted correctly or it’s corrupted.
For this, you can take out the SD card and put it back inside properly. If this doesn’t fix the problem, then put the SD card in some other device to check if the problem is with SD card or your SD card slot.
If that doesn’t help as well, then you will have to format your SD card. But, before formatting, make sure you have backed up your necessary files on the SD card by connecting it to the PC.
Alternatively, if your phone is accepting the SD card but not showing the data inside it, you can also format it from your phone. Just go to Settings, tap on Storage and Format SD Card to delete all the data and reuse it as a new SD card.