My daughter's 15" Mac book pro fell and was hit by a chair. The hard drive was unable to be repaired with the utility and I bought a new bigger drive as replacement ~$80. Mac store wanted $250 to replace the drive, duh. I replaced the drive with the new drive but it was not seen by the cpu but when I attached it using a SATA conversion cable to a USB port it was operational as expected. I replaced the hard drive cable as others here have and it fixed the problem. I just reinstalled the new hard drive internally with the new cable and it was done. This thread was invaluble to me diagnosing the problem. Thanks all. Charles