HT1751: iTunes: Back up your iTunes library by copying to an external hard driveLearn about iTunes: Back up your iTunes library by copying to an external hard drive
Currently Being ModeratedOct 5, 2013 6:39 PM (in response to MD122)
Copy the entire iTunes folder to the external drive.
If you have content that isn't stored in the iTunes Media folder consolidate the library first.
If your iTunes Media folder isn't directly inside the main iTunes folder see Make a split library portable.
Currently Being ModeratedOct 5, 2013 6:34 PM (in response to MD122)
The situation is that I am going to completely reboot my Macbook Air,
Reboot means to restart.
You mean restore the HD.
You should backup the entire HD. Using Time Machine would be easiest.
If you want to reinstall the OS, resart and hold Command R. This boots from the recovery drive.
From here, you can reinstall the OS. Your user folders will remain.
But as always, backup everything before you do anything such as this.