Ok so I'm about to sell my 2012 13" MBP so I can't get the rMBP, but I'm new to Mac and obviously screwed up big time. I went into Disk Utility & selected the erase option which I believe also says it reinstalls the OS. It took about 10 or 15 seconds then a pop up appeared and asked if I wanted to go back into Disk Utility or restart. Everything looked fine so I selected restart. Now when I turn on the MBP it has the folder with a question mark in it. I can't get them computer to do anything. There is no actual disk that came with the computer. How do I get this MBP back up and running? Thanks in advance.