SD card and something about it being mounted

[AC Question]

What does it mean when it says your SD card is unmounted?To use it, it must be mounted, is what it says. What happens if I mount it? I have no idea what any of this means. Please explain,if you can. Thank you very much!

 

[Rukbat]

"your SD card is unmounted" means that the phone doesn't see the card. Turn the phone off, remove the card, wipe the contacts with a tissue, put the card back in and see if it works.

If not, remove it, put it into a USB adapter and see if it works in a PC. If not, the card is probably defective. If it works in a PC, but not in the phone, the SD card port in the phone is probably defective (and has to be replaced by a repair shop).