Firstly, connect your SD card to another device to check whether your SD card is faulty. If your SD card is connected to PC but is still not reading in File Explorer, you can go to Disk Management to check whether drive letter of SD card is missing or disappearing. If it's so, you need to assign a new drive letter to your card and make it recognizable again with the steps below: Open Run dialogue by pressing “Windows” + “R” at the same time. Open Disk Management by inputting "diskmgmt.msc." Find the SD card, right-click the partition on it, then select"Change Drive Letter and Path…". Assign the drive letter of your SD card by clicking "Add" in the pop-up window. I had the same problem before, my SD card not reading, and the data lost. I solve it by using Bitwar Data Recovery. Maybe you can try it.
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