Hey! I have a Macbook PRO 13" 2011 and its harddisk is broken. When turning the macbook on it just shows the apple logo and the loading animation but nothing happens. If I connect the harddisk to my Macbook Retina via USB it takes a while and everything loads slowly but I was able to backup the data. I bought a new harddisk because the guy in the store told me that I just have to connect the new harddisk to my old macbook pro and i can load the IOS directly from the macbook since the license is already set in the mainboard and I just need to connect it via LAN. OK I have tried that but when I start my macbook pro with the new harddisk it just shows me a folder and a questionmark. What should I do? I dont have any disk or dvd delivered with it originally. Can I load the OS on my macbook retina and connect the new harddisk via USB and install the OS on the harddisk? Or is there a combination to press when I start the macbook with the harddisk? Someone told me that I have to formate the new harddisk once, how does this work on my retina? Thanks so much appreciate your help!