Mac OS X Mountain Lion, Permission change makes unable to boot.

[Lasan]

Hi everyone,
I change Everyone No Access on my HD. The system cannot startup now.
After that I try to logout but could not. So I press the power button and shut it down. Then I restart but It can never pass Apple Logo. No spinning gear shows up.

Anyone, please help me know what went wrong and how to fix it.
Actually I am tech savvy but in fear of worsen the problem, I did not do other thing yet.

my machine is MacBook Pro late 2011. core i5, 2.4 GHz, RAM 4GB, running Mountain Lion.

Thanks in advance.
Lasan

 

[DeltaMac]

for "tech savvy", you screwed up now
When you changed the HD permissions to "Everyone no access", you got exactly what you asked for - no access, for everyone (which includes you)

This should fix your problem: (compliments to g/re/p for this)

1) Boot into single user mode, type mount -uw / and press return

2) type chmod 775 /Volumes/'Macintosh HD' and press return

3) type reboot and press return

Change the volume name to whatever yours actually is, if not 'Macintosh HD'