My macbook pro safari is crashed ...i want to reinstall it but how ??

Question

Process:    
Safari [494]
Path:       
/Applications/Safari.app/Contents/MacOS/Safari
Identifier: 
com.apple.Safari
Version:    
6.0 (7536.25)
Build Info: 
WebBrowser-7536025000000000~1
Code Type:  
X86-64 (Native)
Parent Process:  launchd [131]
Date/Time:  
2012-12-04 13:08:35.993 +0600
OS Version: 
Mac OS X 10.7.5 (11G63b)
Report Version:  9
Interval Since Last Report:     
9335 sec
Crashes Since Last Report:      
6
Per-App Crashes Since Last Report:   1
Anonymous UUID:                 
B9675F68-3772-42DE-9C8F-F812AB55D6E9
Crashed Thread:  0
Exception Type:  EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Application Specific Information:
dyld: launch, loading dependent libraries
Dyld Error Message:
  Library not loaded: /System/Library/Frameworks/Accounts.framework/Versions/A/Accounts
  Referenced from: /System/Library/StagedFrameworks/Safari/Safari.framework/Safari
  Reason: image not found
Binary Images:
0x102ed2000 -   
0x102ed2fff  com.apple.Safari (6.0 - 7536.25) <41237DCA-DCCA-34BE-B97E-2398B478CA9F> /Applications/Safari.app/Contents/MacOS/Safari
0x102edc000 -   
0x1033d1fff  com.apple.Safari.framework (8536 - 8536.26.17) <A28655B2-8394-32D4-82C2-725FAD855E48> /System/Library/StagedFrameworks/Safari/Safari.framework/Safari
0x7fff62ad2000 -
0x7fff62b06baf  dyld (195.6 - ???) <C58DAD8A-4B00-3676-8637-93D6FDE73147> /usr/lib/dyld
0x7fff90251000 -
0x7fff9027efe7  libSystem.B.dylib (159.1.0 - compatibility 1.0.0) <6E5C8AC3-DBB7-31CB-BEB7-D6ED8E6DE0CE> /usr/lib/libSystem.B.dylib
Model: MacBookPro8,1, BootROM MBP81.0047.B27, 2 processors, Intel Core i7, 2.8 GHz, 8 GB, SMC 1.68f98
Graphics: Intel HD Graphics 3000, Intel HD Graphics 3000, Built-In, 512 MB
Memory Module: BANK 0/DIMM0, 4 GB, DDR3, 1333 MHz, 0x0000, 0x000000000000000000000000000000000000
Memory Module: BANK 1/DIMM0, 4 GB, DDR3, 1333 MHz, 0x0000, 0x000000000000000000000000000000000000
AirPort: spairport_wireless_card_type_airport_extreme (0x14E4, 0xD6), Broadcom BCM43xx 1.0 (5.106.198.19.22)
Bluetooth: Version 4.0.8f17, 2 service, 11 devices, 1 incoming serial ports
Network Service: Ethernet, Ethernet, en0
Network Service: Wi-Fi, AirPort, en1
Serial ATA Device: TOSHIBA MK7559GSXF, 750.16 GB
Serial ATA Device: MATSHITADVD-R   UJ-8A8
USB Device: hub_device, 0x0424  (SMSC), 0x2513, 0xfd100000 / 2
USB Device: IR Receiver, apple_vendor_id, 0x8242, 0xfd110000 / 3
USB Device: FaceTime HD Camera (Built-in), apple_vendor_id, 0x8509, 0xfa200000 / 3
USB Device: hub_device, 0x0424  (SMSC), 0x2513, 0xfa100000 / 2
USB Device: Apple Internal Keyboard / Trackpad, apple_vendor_id, 0x0252, 0xfa120000 / 5
USB Device: BRCM2070 Hub, 0x0a5c  (Broadcom Corp.), 0x4500, 0xfa110000 / 4
USB Device: Bluetooth USB Host Controller, apple_vendor_id, 0x821a, 0xfa113000 / 7

Answer 1

Back up all data.
Boot into Recovery by holding down the key combination command-R at the startup chime. Release the keys when you see a gray screen with a spinning dial.
Note: You need an always-on Ethernet or Wi-Fi connection to the Internet to use Recovery. It won’t work with USB or PPPoE modems, or with networks that require any kind of authentication other than a WPA or WPA2 Personal password.
When the OS X Utilities screen appears, follow the prompts to reinstall the OS. You don't need to erase the boot volume, and you won't need your backup unless something goes wrong. If your Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade, so make a note of those before you begin.