Re: How to format microSD card
1) If you restart the phone in recovery mode. Turn the phone off. Press both Volume Up and Power until Recovery mode comes up (about 15 seconds). You should see a menu item to format the SD card (in the phone, not plugged into the computer).
2) If you're formatting a card that you want to be readable by both the phone and a computer, use FAT32 (or exFAT if it's a large card). NTFS is readable by Windows but not by other operating systems (in most cases).
3) The phone puts certain folders on the card that Windows doesn't, so it's better to format in the phone.
4) The only reason to format the card is if the current formatting is messed up. If the card can be used there's no reason to format it. (Formatting an SD card isn't like formatting a hard drive - it doesn't erase data.)