The best way to recover Windows boot is by Recovery Console provided by Microsoft.

To start the Windows Recovery Console, use one of the following methods:
• Use the Windows Setup floppy disks or the Windows CD-ROM to start your computer. At the "Welcome to Setup" screen, press F10 or press 'R" to repair.
• Use the Winnt32.exe utility with the /cmdcons option to add the Windows Recovery Console to the Windows Startup folder. This procedure requires approximately 7 megabytes (MB) of hard disk space on the system partition to hold the Cmdcons folder and files.

Using the Command Console
After you start the Windows Recovery Console, you receive the following message:
Microsoft Windows(R) Recovery Console

The Recovery Console provides system repair and recovery functionality.
Type EXIT to quit the Recovery Console and restart the computer.

1: C:\WINDOWS

Which Windows Installation would you like to log on to
(To cancel, press ENTER)?
After you enter the number for the appropriate Windows installation, Windows will then prompt you to enter the Administrator account password.

Note If you use an incorrect password three times, the Windows Recovery Console quits. Also, if the Security Accounts Manager (SAM) database is missing or damaged, you cannot use the Windows Recovery Console because you cannot have correct authentication. After you enter your password and the Windows Recovery Console starts, type exit to restart the computer.

When you use Windows XP Professional, you can set group policies to enable automatic administrative logon.

Available commands
HELP
Use the help command to list all the following supported commands:

attrib del fixboot more set
batch delete fixmbr mkdir systemroot
bootcfg dir format more type
cd disable help net
chdir diskpart listsvc rd
chkdsk enable logon ren
cls exit map rename
copy expand md rmdir

Use the following commands to fix boot problems:

BOOTCFG
Use this command for boot configuration and recovery. This command has the following options:
bootcfg /add
bootcfg /rebuild
bootcfg /scan
bootcfg /list
bootcfg /disableredirect
bootcfg /redirect [portbaudrate] | [useBiosSettings]
Examples:
bootcfg /redirect com1 115200
bootcfg /redirect useBiosSettings
You can use the following options:
/add : Adds a Windows installation to the boot menu list.
/rebuild : Iterates through all Windows installations so that you can specify which installations to add.
/scan : Scans all disks for Windows installations and displays the results so that you can specify which installations to add.
/default : Sets the default boot entry.
/list : Lists the entries already in the boot menu list.
/disableredirect : Disables redirection in the boot loader.
/redirect : Enables redirection in the boot loader, with the specified configuration.


FIXBOOT
fixboot drive name:
Use this command to write the new Windows boot sector code on the system partition. In the command syntax, drive name is the drive letter where the boot sector will be written. This command fixes damage in the Windows boot sector. This command overrides the default setting, which writes to the system boot partition. The fixboot command is supported only on x86-based computers.
FIXMBR
fixmbr device name
Use this command to repair the MBR of the boot partition. In the command syntax, device name is an optional device name that specifies the device that requires a new MBR. Use this command if a virus has damaged the MBR and Windows cannot start.

Warning This command can damage your partition tables if a virus is present or if a hardware problem exists. If you use this command, you may create inaccessible partitions. We recommend that you run antivirus software before you use this command.

You can obtain the device name from the output of the map command. If you do not specify a device name, the MBR of the boot device is repaired, for example:
fixmbr \device\harddisk2
If the fixmbr command detects an invalid or non-standard partition table signature, fixmbr command prompts you for permission before rewriting the MBR. The fixmbr command is supported only on x86-based computers.

That's it.