At least once in a lifetime, one day, you turn on your computer as usual and it won't start. It is not Windows that does not load, there is just an initial problem because the boot stops immediately with an error message which, for example can be: " Operating System not found " or " disk boot failure " or worse, " a disk read error occurred. Press Ctrl + Alt + Del to restart ".
When the message of the operating system not found the solution appears, 90% is found and you can restore the correct startup of Windows .
The error on the disk, on the other hand, most likely depends on an internal problem on the computer hardware and does not have an easy solution (we will talk about it another time).
When the Windows operating system does not load the error it is in the boot loader or in the MBR, that is the Master Boot record which, for some obscure reason, has become corrupt.
Using the Windows utility called Fixmbr, Bootrec or Bootsect, you can restore Windows startup and restart your computer without having to reformat or pay a technician .
READ ALSO: What happens when the computer is turned on and why it can fail
MBR is a set of data that form the first sector of a disk.
In very simple words, it is the instruction, stored on the hard disk, that tells the computer to boot an operating system when you turn it on.
When installing multiple operating systems on a PC (eg Windows and Linux or Windows 7 and Windows 10) and creating a dual boot, when creating, modifying or deleting partitions of a disk, when using defragmentation programs or tools acting on the hard disk, if you are affected by viruses or malware or in the event of abnormal events, the MBR and the boot loader can be damaged .
If there are computer startup errors and no disk partitions become accessible from the operating system, the computer cannot find anything to load and freezes immediately with an error message.
Fortunately, recovering the MBR and the boot loader with Windows 7 and Windows 10 and correcting the errors is quite easy and within everyone's reach.
So if you get errors at boot of Windows 7 and Windows 10, you can do this:
NOTE: Go to the following article if you need to resolve the "Cannot find an operating system" error on Windows 10
1) Insert the Windows 7 installation DVD or the Windows 10 USB stick and start the computer from the CD player or from USB.
To boot the PC from CD ROM or USB, you can generally access the boot menu by pressing F12 or from the bios by changing the boot load order.
With Windows 10 and Windows 8.1 the installation DVD may not be needed because after the computer fails to start twice, the recovery screen should appear so that you can use the commands that make the Boot and MBR Fix.
2) Go ahead when the choice of language appears.
3) Instead of clicking on " Install Windows 7 ", below you must click on the item Repair your computer to access the screen of options for restoring Windows.
4) Press on the last line, the one where Command Prompt is written to access the black DOS interface.
5) In Windows 10, to restore the boot loader and the PC boot, you need to run the following commands:
- bootrec / fixmbr
- bootrec / fixboot
- bootrec / scanos
- bootrec / rebuildbcd
- exit
If that doesn't work, you can try this other route with the following commands:
- diskpart
- sel disk 0
- list vol
To find the EFI partition number, then type:
- sel vol X (instead of X write the volume number of the EFI FAT32 partition)
- assign letter = w:
- exit
To restore the Windows 10 boot loader, finally, type these commands:
- cd / d W: \ EFI \ Microsoft \ Boot \ (specify the drive letter chosen previously, in this case the W)
- bootrec / fixboot
- ren BCD BCD.bak
- bcdboot C: \ Windows / l it-it / sw: / f ALL
READ ALSO: Stop the Windows 10 automatic recovery loop
In Windows 7 the commands for Fix MBR are:
- bootrec / rebuildbcd
- bootrec / fixmbr
- exit
If that doesn't work, go back to the command prompt and also run the command:
bootsect / nt60 c: / MBR
or
bootsect / nt60 SYS
To automatically restore boot from partition C.
If the bootsect command is not found, navigate to the Windows 7 DVD directory.
From the starting position, X: \ Sources, write D: and press enter; then write Dir to verify that it is the DVD or if it is another partition.
If there are more disks, more partitions, look for the DVD directory by going in alphabetical order, then writing E :, F: and so on.
If the DVD is in D :, write cd boot - Enter, run the bootsect command as seen before.
While bootrec.exe / fixmbr allows you to restore the master boot record and repair the boot process of the computer, the bootrec.exe / fixboot command rewrites a new boot record on the partition while bootrec.exe / rebuildbcd rebuilds the Boot Configuration Data .
6) Close the command prompt and restart the computer without cd inside.
Then there are some small programs that allow advanced MBR management and bootloader recovery :
1) Hiren CD if the PC does not start, it allows you to load all the utilities to restore the boot loader and fix the MBR.
HIren CD should be started when the computer is turned on by changing the boot order at startup.
2) Super Grub is the program to use if the PC no longer starts, an ISO to burn to CD.
Boot your PC from CD and then use SuperGrub to repair the damaged bootloader.
3) MBR Wizard allows you to save the MBR and restore it in case it gets damaged.
To backup, run the command: MBRWiz / save = MBR / filename = D: \ backupMBR
For the restore instead: MBRWiz / restore = MBR / filename = D: \ backupMBR
4) MBRFix is a command line tool for Windows that can be used to launch advanced commands that manipulate the MBR.
5) MBRTool can be used to backup all MBR automatically, or to work with specific master boot records.
Being a graphical interface it is a little simpler than MBRFix.
6) BOOTICE is a truly complete portable program that allows you to restore the MBR of both the internal hard disk and an external hard disk or a USB stick, to backup the first sector of the disk, to modify the BCD file (Boot Configuration Data), to create disk images and to install different types of MBR.
7) HDHacker is perhaps the easiest on the list for backing up and restoring any sector of a partition, including the MBR sector.
If the system still does not boot, save everything if Windows does not start and the computer does not turn on .
As a final solution, what almost always works is the reinstallation or installation of Windows 7 with a custom procedure.
Old data is saved to a windows.old folder and will not be lost.
If, after reinstalling Windows 7 or after formatting, the computer still does not start, there is a hardware problem that can be solved only by changing the hard disk in the computer and using the damaged one as a "slave"; maybe we talk about this better on a high occasion.
