Fix a Corrupted Windows

There are times when Microsoft Windows XP will not start due to a corruption in the Windows registry. In order to recover from this corrupted registry, there are a few steps that must be followed. Taking these steps may not completely fix the problem, depending on the cause, but this will help recover lost files.
Instructions

Creating a Registry Back-up

Place the Windows XP start-up disk into the CD-ROM drive or into the floppy disk drive. Restart the computer.

Select options that are needed to start the computer using the CD-ROM if you are prompted.

Press "R" in order to start the Microsoft Recovery Console when the "Welcome to Setup" screen shows up on your computer.

Type in the administrator password when asked to do so. If there is no password with the administrator's account, simply press "Enter."

Type in the following lines, being sure to add a page break after each one.

md tmp

copy c:\windows\system32\config\system c:\windows\tmp\system.bak

copy c:\windows\system32\config\software c:\windows\tmp\software.bak

copy c:\windows\system32\config\sam c:\windows\tmp\sam.bak

copy c:\windows\system32\config\security c:\windows\tmp\security.bak

copy c:\windows\system32\config\default c:\windows\tmp\default.bak

del c:\windows\system32\config\system

del c:\windows\system32\config\software

del c:\windows\system32\config\sam

del c:\windows\system32\config\security

del c:\windows\system32\config\default

copy c:\windows\repair\system c:\windows\system32\config\system

copy c:\windows\repair\software c:\windows\system32\config\software

copy c:\windows\repair\sam c:\windows\system32\config\sam

copy c:\windows\repair\security c:\windows\system32\config\security

copy c:\windows\repair\default c:\windows\system32\config\default

Type in the word "exit" on the screen to quit the recovery. Wait for your computer to restart.
Start Windows in Safe Mode

Choose "Start" or the Windows icon in the bottom left-hand part of your screen. Choose "Shut Down" or "Turn Off Computer" and then select "Restart" from the drop-down menu. Click "OK".

Press the "F8" key to start the computer in safe mode when you reach the start-up menu.

Select the safe mode option with your arrow keys and press "Enter." Run Windows Explorer when the system starts up. Select "Folder Options" from the "Tools" menu. Select the "View" tab.

Under "Hidden Files and Folders," check the box that says "Show hidden files and folders" and un-check the box that says "Hide protected operating system siles". Select "OK" or "Yes" if a dialog box comes up.

Open the drive where Windows XP is installed by double-clicking it. All files will then be shown.

Open the "System Volume Information" folder. This folder is a hidden folder, extremely protected and may appear in a lighter color than the rest of the folders.

View all of the folders' properties and check the time that they were created until you find one that was not created at the current time. Open that folder. It should be a folder with RPx underneath of it. This is a restore file.

Locate a "Snapshot" folder within the one you just opened. It will have "Snapshot" written on the end of the file name.

Copy the following files to the C:\Windows\Tmp folder.
_REGISTRY_USER_.DEFAULT
_REGISTRY_MACHINE_SECURITY
_REGISTRY_MACHINE_SOFTWARE
_REGISTRY_MACHINE_SYSTEM
_REGISTRY_MACHINE_SAM

Rename all of these files in the same order as below.
Change the _REGISTRY_USER_.DEFAULT file to DEFAULT
Change the _REGISTRY_MACHINE_SECURITY file to SECURITY
Change the _REGISTRY_MACHINE_SOFTWARE file to SOFTWARE
Change the _REGISTRY_MACHINE_SYSTEM file to SYSTEM
Change the _REGISTRY_MACHINE_SAM file to SAM
Delete Existing Registry Files and Copy System Restore Files

Start the Recovery Console again.

Type the following lines into the command prompt, being sure to make a page break after each line.

del c:\windows\system32\config\sam

del c:\windows\system32\config\security

del c:\windows\system32\config\software

del c:\windows\system32\config\default

del c:\windows\system32\config\system

copy c:\windows\tmp\software c:\windows\system32\config\software

copy c:\windows\tmp\system c:\windows\system32\config\system

copy c:\windows\tmp\sam c:\windows\system32\config\sam

copy c:\windows\tmp\security c:\windows\system32\config\security

copy c:\windows\tmp\default c:\windows\system32\config\default

Type "exit" and allow the computer to restart.

Click "Start" and then choose "All Programs" from the menu.

Select "Accessories" and double-click it. Next, click "System Tools."

Choose "System Restore" and then select the option that says, "Restore to a previous Restore Point."
http://www.livetechcare.com