Hi there, On clicking the startup button, my MacBook Pro chimes, shows the apple logo and the the progress bar reaches approx 25%-30% before it stalls and does not progress further. It shuts down after several minutes if left unattended. I've tried starting in: 1) safe mode (shift key) to no avail. Same issue, 2) recovery mode (shift+R) which when prompted with the Utilities I could not Repair the HD (simply states the hard disk could not be repaired and to re-install the OSX), 3) have just tried resetting the parameter RAM (****+option+P+R), to no avail. Same result as #2 above. I don't have a backup disk or Boot disk (owing to loss in house move, but that's a poor excuse, I know), nor was I running Time Machine. Short of taking it to my local store can anyone suggest whatelse I might do? Thanks! MacBook Pro, circa 2011-12. It came pre-installed with OSX Lion, but I upgraded it 12 months ago to Yosemite.