fixboot,fixmbr
Boot - αρουμε απο το DVD με τα Vista - 7 και τρέχουμε command line απο Recovery Console για να κανουμε επιδιόρθωση MBR & bootsectors

Οπου x: το γράμμα του CD-Drive

Vista:
bootrec.exe /fixmbr x:\boot\bootsect.exe /nt60 all /force

Windows 7:
bootrec.exe /fixmbr bootsect.exe /nt60 all /force

Rebuild your BCD:
attrib -h -s C:\boot\BCD del C:\boot\BCD bootrec.exe /rebuildbcd

Αν όλα πάνε καλά , θα βγάλει ενα μύνημα οτι είναι ΟΚ

Aν χασουμε τον bootloader των windows απο τον grub ή lilo τοτε απλα δινουμε
bootrec /fixmbr
bootrec /fixboot


Δώστε την παρακάτω εντολη για επανεκκινηση.
shutdown -r -t 0


Bootrec

/FixMbr

The /FixMbroption writes a Windows 7 or Windows Vista-compatible MBR to the system partition. This option does not overwrite the existing partition table. Use this option when you must resolve MBR corruption issues, or when you have to remove non-standard code from the MBR.

/FixBoot

The /FixBoot option writes a new boot sector to the system partition by using a boot sector that is compatible with Windows Vista or Windows 7. Use this option if one of the following conditions is true:
  • The boot sector has been replaced with a non-standard Windows Vista or Windows 7 boot sector.
  • The boot sector is damaged.
  • An earlier Windows operating system has been installed after Windows Vista or Windows 7 was installed. In this scenario, the computer starts by using Windows NT Loader (NTLDR) instead of Windows Boot Manager (Bootmgr.exe).

/ScanOs

The /ScanOs option scans all disks for installations that are compatible with Windows Vista or Windows 7. Additionally, this option displays the entries that are currently not in the BCD store. Use this option when there are Windows Vista or Windows 7 installations that the Boot Manager menu does not list.

/RebuildBcd

The /RebuildBcd option scans all disks for installations that are compatible with Windows Vista or Windows 7. Additionally, this option lets you select the installations that you want to add to the BCD store. Use this option when you must completely rebuild the BCD.


Bootsect

bootsect.exe {/help | /nt52 | /nt60} {SYS | ALL | <DriveLetter:>} [/force]
For example, to apply the master boot code that is compatible with NTLDR to the volume labeled E, use the following command:
bootsect.exe /nt52 E:



/help
Displays these usage instructions.
/nt52
Applies the master boot code that is compatible with NTLDR to SYS, ALL, or <DriveLetter>. The operating system installed on SYS, ALL, or <DriveLetter> must be a previous version of Windows Vista.
/nt60
Applies the master boot code that is compatible with BOOTMGR to SYS, ALL, or <DriveLetter>. The operating system installed on SYS, ALL, or <DriveLetter> must be Windows Vista.
SYS
Updates the master boot code on the system partition used to boot Windows.
ALL
Updates the master boot code on all partitions. ALL does not necessarily update the boot code for each volume. Instead, this option updates the boot code on volumes that can be used as Windows boot volumes, which excludes any dynamic volumes that are not connected with an underlying disk partition. This restriction is present because boot code must be located at the beginning of a disk partition.
<DriveLetter>
Updates the master boot code on the volume associated with this drive letter. Boot code will not be updated if either 1) <DriveLetter> is not associated with a volume or 2) <DriveLetter> is associated with a volume not connected to an underlying disk partition.
/force
Forcibly dismounts the volume(s) during the boot code update. You must use this option with caution.

If Bootsect.exe cannot gain exclusive volume access, then the file system may overwrite the boot code before the next reboot. Bootsect.exe always attempts to lock and dismount the volume before each update. When /force is specified, a forced dismount is attempted if the initial lock attempt fails. A lock can fail, for example, if files on the destination volume are currently opened by other programs.

When successful, a forced dismount enables exclusive volume access and a reliable boot code update even though the initial lock failed. At the same time, a forced dismount invalidates all open handles to files on the destination volume. This can result in unexpected behavior from the programs that opened these files. Therefore, use this option with caution.