So I got a macbook air from a friend and wanted to wipe everything from the computer. I followed the steps from a youtube video (which might have been my error) but after I erased everything from the Macintosh HD drive I went to “Reinstall OS X”, as it was running on OS X El Capitan, and when I get to the part that says to login to app store to download, I keep getting the same pop-up window saying, “Item is temporarily unavailable. Try again later.” Anyone know anything that could help me??