>Free download AOMEI Partition Assistant. Install it to your computer based on Windows 10/8/7/Vista/XP.
> Connect your SD card to the computer installed with AOMEI Partition Assistant.
Then, you can follow the steps to format unformattable SD card.
Step 1. Launch AOMEI Partition Assistant. It will display you the basic situation of your hard disks on your computer. Here you can see the SD card marked as“Unformatted”. To format it, here you can right-click the partition, select Format Partition in the pop-up menu.
Step 2. Here you can edit the Partition Label, choose File System, and change cluster size. AOMEI Partition Assistant allows you to format partition to NTFS, FAT32, Ext2, Ext3, Ext4, exFAT. Choose the one you need, and click OK to continue.
Step 3. You will back to the main interface. Here you can see the SD card has turned to NTFS file system. But it isn’t done, you need to click Apply at the toolbar to execute the progress.
It would take a few minutes. Wait till the progress done, and you can exit the program. After that, the SD card can be used normally.