How to recover from a corrupted registry that prevents Windows 2000/XP from starting

How to recover from a corrupted registry that prevents Windows 2000/XP from starting

For Windows 2000, you may try to download ‘Windows 2000 Registry Repair Utility’. You will also need Windows XP Professional Setup disk.
http://www.microsoft.com/downloads/details.aspx?familyid=56d3c201-2c68-4de8-9229-ca494362419c&displaylang=en

If you don’t have access to another computer, you can use Recovery Consol to replace and repair registry.

You could install Recovery Console in two way:
(1) Select options to start the computer from the CD-ROM drive. Insert the Windows 2000/XP CD-ROM, and then restart the computer. When the "Welcome to Setup" screen appears, press R to start the Recovery Console, or
(2) Use Windows 98 bookdisk to boot into DOS. Insert the Windows 2000/XP CD and type D:\i386\winnt32.exe /cmdcons, where D is your CD Rom drive. Reboot the computer, select Recovery Console.

Login as Administrator and enter the password. At the command prompt, enter the following:

Depended on which corrupted registry entry, select one or all suit your need. (Replace C:\Windows with your Windows 2000/XP folder.)

Backup current registry:
rename c:\windows\system32\config\system c:\windows\system32\system.bak
rename c:\windows\system32\config\software c:\windows\system32software.bak
rename c:\windows\system32\config\sam c:\windows\system32\sam.bak
rename c:\windows\system32\config\security c:\windows\system32\security.bak
rename c:\windows\system32\config\default c:\windows\ system32\default.bak

Replace current registry with default registry:
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 exit to quit Recovery Console. Your computer will restart.

In these procedures, you might lose some Windows settings. For Windows XP, you could do a System Restore to restore the setting a day early that you had problem.