Your memory card is not detected in phone or computer.
When inserted in computer, see if you can see this card in Disk Management (Right Click on computer >> Manage >> Disk Management) - if detected, it should have a drive letter assigned to it (like D: or G: etc. ) if there is no drive letter assigned but card is showing, you would need to assign it a drive letter.
If card is not detected in Disk Management, it might have gone bad. Good luck!!