Ok, so today i was testing my MacBook air file sharing feature with a pc with linux mint. Everything was ok, suddenly I noticed that my mac was sharing the Macintosh HD folder too, so i decided to modify the sharing permissions of the Macintosh HD in my mac. Suddenly everything just went wrong: my linux pc stopped responding, i had to turn it off the hard way. But also my mac crashed, also turned it off the hard way. When I turned it on again and after logging in, the loading screen stops responding: Did I mess up? How do I fix it, should I try cmd+R? , please help me i am desperated, the thing is not even six months old (early 2014 model).