To use fsck, you must run it from the command line. Unlike using your mouse to open an application to do something, you'll need to type a text command at the prompt (#) to tell fsck what to do. The Terminal application (/Applications/Utilities) and single-user mode are two examples of command-line interfaces in which you can type such commands. To use fsck:
1. Start up your computer in single-user mode to reach the command line. Hold CMD+s keys down at bootup.
Note: If necessary, perform a forced restart as described in the Emergency Troubleshooting Handbook that came with your computer. On desktop computers, you can do this by pressing the reset/interrupt button (if there is one) or holding down the power button for several seconds. On portable computers, simultaneously press the Command-Control-power keys. If your portable computer doesn't restart with this method, you may need to reset the Power Manager.
2. At the command-line prompt, type /sbin/fsck -fy
(SPACE between fsck AND -fy important)
3. Press Return. fsck will go through five "phases" and then return information about your disk's use and fragmentation. Once it finishes, it'll display this message if no issue is found:

The volume (name
ofvolume) appears to be OK 
If fsck found issues and has altered, repaired, or fixed anything, it will display this message:

*** FILE SYSTEM WAS MODIFIED
*** 

Important: If this message appears, repeat the fsck command you typed in step 2 until fsck tells you that your volume appears to be OK (first-pass repairs may uncover additional issues, so this is a normal thing to do).
4. When fsck reports that your volume is OK, type reboot at the prompt and then press Return.
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Then Safe Boot from the HD, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, reboot when it completes.
