Have been given a 2013 MacBook Air. It has been backed up with time machine and the hard drive wiped. When i restarted upon receipt the hard drive was not mounted. Have tried to remount but now all I get when rebooting is a folder with a question mary !
You need to perform a clean install of macOS by booting into Recovery Mode, Internet Recovery Mode, or from a bootable macOS USB installer. Even though the SSD may be "erased", the previous owner may only have erased the "Macintosh HD" volume instead of the whole physical drive. Once you boot the macOS installer you need to erase the whole physical SSD. With later versions of Disk Utility Apple hides the physical drive from view so you must first reveal the drive within Disk Utility. This Apple article shows how to have Disk Utility reveal the physical drive so you can erase the "Apple SSD....." item:
https://support.apple.com/guide/disk-utility/erase-and-reformat-a-storage-device-dskutl14079/mac
Recovery Mode:
https://support.apple.com/kb/HT201314
Internet Recovery Mode:
https://support.apple.com/kb/HT204904
Creating a bootable macOS USB installer:
You need to perform a clean install of macOS by booting into Recovery Mode, Internet Recovery Mode, or from a bootable macOS USB installer. Even though the SSD may be "erased", the previous owner may only have erased the "Macintosh HD" volume instead of the whole physical drive. Once you boot the macOS installer you need to erase the whole physical SSD. With later versions of Disk Utility Apple hides the physical drive from view so you must first reveal the drive within Disk Utility. This Apple article shows how to have Disk Utility reveal the physical drive so you can erase the "Apple SSD....." item:
https://support.apple.com/guide/disk-utility/erase-and-reformat-a-storage-device-dskutl14079/mac
Recovery Mode:
https://support.apple.com/kb/HT201314
Internet Recovery Mode:
https://support.apple.com/kb/HT204904
Creating a bootable macOS USB installer:
Flashing folder with question mark
