Hi, Yesterday evening I awoke my computer (2011 13 in MBP) and the only thing on the screen was a folder flashing with a question mark. I searched and tried: restart a couple of times, reset PRAM, and holding option down when starting. Holding option down when restarting showed the only option as network recovery. So, I downloaded that and in disk utilities, the hard drive didn't show up. I replaced the hard drive and held option down when starting and again the network was the only option. I went through the network recovery download and again disk utilities did not show any hard drive. Then, I put the original hard drive (that worked fine yesterday morning) in an external enclosure, held down the option key during startup, and it found the startup disk just fine. I have restarted several times and am using the computer right now using the external boot method. So, my questions to the experts: 1) is there anything cheap and easy (settings or startup options) I should try and get the internal hard drive slot working? 2) the sata ribbon cable and connector visually look fine as does the connector on the motherboard. Is replacing the cable likely to help? 3) if the motherboard sata connector, or something else, is faulty, is there a diagnostic to check that? 4) if I just can't get it working, would the least expensive option be to just remove the optical drive and stick the hard drive in there? Thanks for reading/helping!