Friday 13 January 2012

How to Fix MBR in Windows Machines

Today the topic is "How to fix MBR in Windows XP, Vista and window 7 ?". This article will help you to understand the MBR and its easy reapir.This article is also related to Security,You may wanna ask that , How ? ... Thats Because bad hackers also make such virus,which can delete your MBR records to corrupt your window... Now you should know that How you can Repair it within 3-4 minutes.So lets start with ...

What is the MBR ?
Generally speaking the processor of your PC is yet to begin its processing once you switch it on. When your system memory is empty the processor doesn’t really have anything that it can execute. Actually your processor has no idea where it is.
The manufacturers of BIOS and other chip makers have developed a way in which you can ensure that your PC can boot regardless of the BIOS in the machine. This will allow your
processor to start executing its process from the same place every time it is switched on. That place is recorded as FFFF0h. 
Every hard disk also has to have a consistent starting point. This is where all the key information is stored regarding the disk. The particulars of this information could include the partitions and their types etc. The BIOS also needs a place where it can load the initial boot program which will start the process known as master boot record. It can be referred to as master boot sector, boot sector or simply MBR.

The exact consistent location of the master boot record is cylinder 0, head 0 and sector 1 which is the first available sector on the disk. This is the place where the BIOS will look when it begins to boot the machine. It will find all the instructions and information regarding the way in which the disk has to be booted and how the operating system should be loaded.

The master boot record consists of three main structures. The first of these is the Master Partition Table. This is a small table that contains all the descriptions regarding the partitions on the hard disk. Only the information that describes four partitions can fit in the master partition table. This is the reason a hard disk is known to have only four true partitions. The partition marked active is the one which is used for booting.

The second most important structure is the Master Boot Code. The initial program that the BIOS has to load and execute in order to start the boot process is contained in the master boot record. The control is eventually transferred to that particular hard disk partition which contains the boot program which has to be used for booting the computer.
Serious data loss can occur if the master boot record is damaged or corrupted in any way. This contains extremely important information and the user will suffer grievous consequences if this information is lost. Most viruses are targeted at the master boot code because this is the first program that is executed when a PC is switched on.
Why MBR get Damaged ?
If, for any reason, the MBR becomes damaged or corrupt, then the operating system will be unable to load.Reason can be anything like :- Due to a Virus,Due to some malware Software or may be due to sudden power switch off.You will normally see error messages like:

1.) Error loading operating system

2.) Missing operating system

3.) Invalid partition table

These messages are definitely not fun,Especially if you are not familiar with computers.Most people would automatically assume their computers are dead ! However, that’s not true. Being in IT myself, these errors are actually referably to other types of Windows errors. Why ? Well, it’s actually fairly easy to fix the Master Boot Record ( MBR ) in XP and Vista. All you have to do is load up the Recovery Console and run a simple command. All of your data, applications, settings, etc are still intact on the drive and once the MBR is fixed, the computer will load normally.

So how can you repair your damaged MBR ?
Here are the steps to follow explained:-

Fix MBR in Xp

1.) First, restart your computer with the Windows XP setup disk in the CD drive. If you don’t have your original disk, borrow one or download a ISO image from a torrent site.
2.) When prompted, boot from the CD drive by pressing any key. If Windows loads automatically, you will first have to enter the BIOS setup and change the order of the boot devices to start with the CD drive.
3.) Once the setup loads, you will see the option to press R to repair a Windows installation.
4.) Once the Recovery Console loads up, you will have to type in a number that corresponds to your Windows installation. This is normally just 1. Press Enter and then type in the Administrator password.
5.) Now at the prompt, type in fixmbr. Your damaged MBR will now be replaced with a new master boot record and your computer should now be able to boot properly. Note that you may also want to run the fixboot command to repair the boot sector with a new one.Also, make sure you only use these commands on a system with one operating system installed. If you have more than one operating system installed, fixmbr and fixboot could mess up everything.

Fix MBR in Vista

In Vista, the procedure to fix the master boot record is a bit different. You have to start up Vista in the Recovery Environment and then run the bootrec command. Here’s how...

1.) First, load up the Windows Vista disc in your drive and press any key to boot from the disc.

2.) Choose the language, time, currency, etc and click Next. Now click on Repair Your Computer.
3.) Choose the operating system to repair and click Next. When the System Recovery Options dialog comes up, choose the Command Prompt.

4.) Now type bootrec.exe and press Enter. This will rebuild the boot configuration data and hopefully fix your problem. You can also run the command with switches to fix just the master boot record (/fixmbr), the boot sector (/fixboot), or rebuild the entire BCD (/rebuildbcd).

Fix MBR in Window 7

  1. Insert your Windows 7 installation DVD in DVD drive.
  2. Restart your computer and boot from your DVD drive (to do this you firstly need to go to your BIOS and set your PC to bootup from the DVD drive).
  3. When asked, boot from the DVD by pressing  F10 or any key on your keyboard.
  4. Now, check your Language, Time,  and Keyboard Input in the proper section and press the Next button.
  5. Now click on Repair Your Computer to gain access to the System Recoverywindow.
  6. Click Command Prompt.
  7. Type one of these following commands and hit Enter:
  • bootsect /nt60 C:\ (to type if your operating system is installed in C:   Of course you can change C: with the word of the partition where your OS is installed)
  • bootsect /nt60 SYS (to use if the first command doesn’t work)
  • bootsect /nt60 ALL (to use if the above commands do not work)
  • Once done, eject the disc and restart your computer for the change to take effect.
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