Original post : bootrec - Guide for Windows XP, Vista, 7, 8, 8.1, 10.
If you can't boot into your Windows Vista system or don't have the original installation disc, use Easy Recovery Essentials and run Command Prompt. Download Easy Recovery Essentials and burn it to any CDs, DVDs or USBs.
bootrec.exe
If Repair Your Computer is not available, System Recovery Options is not installed on your system. Access Command Prompt from the installation disc or use Easy Recovery Essentials.
bootrec /rebuildbcd
If you can't boot into your Windows 7 system or don't have the original installation disc, use Easy Recovery Essentials and run Command Prompt. Download Easy Recovery Essentials and burn it to any CDs, DVDs or USBs.
If you can't boot into your Windows 8/8.1 system or don't have the original installation disc, use Easy Recovery Essentials and run Command Prompt. Download Easy Recovery Essentials and burn it to any CDs, DVDs or USBs.
bootrec /FixMbr
exit
Shift + F8 doesn't always work, as reported by some users. If this is the case for your system, consider using Easy Recovery Essentials to run Command Prompt - details below this section of steps.
If you can't boot into your Windows 10 system or don't have the original installation disc, use Easy Recovery Essentials and run Command Prompt. Download Easy Recovery Essentials and burn it to any CDs, DVDs or USBs.
bootrec /FixBoot
bootrec /ScanOs
bootrec /RebuildBcd
bcdedit /export C:\BCDBackup
c:
cd boot
attrib bcd -s -h -r
ren c:\boot\bcd bcd.old
Total identified Windows installations: 0
ren c:\bootmgr bootmgrbackup
Element not found
diskpart
list disk
select disk 0
0
list partition
select partition 0
active
This solution works only if you have the original Windows 7 installation disc. Otherwise, use Easy Recovery Essentials to access Command Prompt or run Automated Repair for automatic repairs.
diskpart select disk 0 list volume
D:
exit D: cd boot dir
bootsect /nt60 SYS /mbr
diskpart sel disk 0 list vol
sel vol 2
2
assign letter=x:
DiskPart successfully assigned the drive letter or mount point.
x:
cd /d x:\EFI\Microsoft\Boot\
bootrec /fixboot
ren BCD BCD.Backup
bcdboot c:\Windows /l en-us /s x: /f ALL