I bought a mac book pro, mid 2012, retina version- from somebody I didn't know, off of craigslist. First mistake. It seemed to work fine, but after awhile it started freezing often and then the folder with a question mark started to appear. I was told that all I had to do was make a bootable USB drive and restart it from that, and it would solve the problem. This computer has no disk drive, so that seemed to be the easiest fix, and I put it off until today when I tried to solve the problem. I know how to use a mac, as an artist, but when it comes to fixing or partitioning and hard drives.. I know little to non. Well, today I managed to download mavericks on my old iMac desktop and then use diskmaker to make a USB with mavericks on it. It took me all day. I should have stopped then. Next I followed a tutorial on how to boot from the USB, and thats when I think I really screwed things up. Everything seem to be going well, until they started talking about partitioning and GUID. What I did- I clicked on Macintosh HD and I deleted it...Then I went to reboot and it said it couldn't reboot from USB drive because it wasn't partitioned. so I went back and I clicked on the USB in disk utility and I tried to partition that, I did 1 partition, made sure it was mac os extended (journaled) and Guild. then I tried to install Os x by clicking on Microsoft HD... I think this tutorial was incorrect about deleting the HD or I don't know how to partition I got confused here "Make sure you have a partition larger than your Macintosh HD and the drive is formatted as Mac OS Extended (Journaled) with the GUID partition table." It started to download everything seemed like It may have worked, I got happy,....and then boom fail. It said my Microsoft HD had been damaged and when I restarted the computer or went back to disk utility is now completely gone. So, at the top it just has the USB drive and in the box below I have a disk 1 and a disk 2 (Im not sure what any of this really means). It got to a point where it gave me a log screen of everything that happened so maybe I could figure it out, but it might as well be in a different language.. actually it is a different language. So, now I have no Microsoft HD... and I have no idea what to do from here. Before I did this, I backed up the computer on a external hard drive, my passport for mac, and I wonder if that could take me back to where I was before I did all this damage. I need some major help. I don't know how I damaged my computer or how it got this bad, when it seemed like it would be so simple. partitioning in disk utility screwed me up because I don't understand it. maybe I was looking at the wrong toturial- it was a how to boot from a USB if your mac has no recovery startup. Which I don't know if that was the case. Did I destroy the computer? Can I get a Microsoft HD back? Can I reboot from the passport? Any ideas? One last thing, before I did this, a person who works on computers but who lives far away looked at the computer and said the diagnosis of the computer seemed that everything was good. But somebody had deleted the operating system or he couldn't find the operating system file. So, I came home and tried to do it myself and now I'm devastated, wondering how I made things so bad, so quick. I know this is a big problem to take on, or it feels like it to me, but I still haven't given up. any advice will be truly appreciated!!! Thanks, starving artist who bought a bad computer.