When you’re having boot problems on your Windows PC it can often be repaired by repairing the MBR (Master Boot Record) which restores the Windows 7 boot loader. You can do it easily with the help of Windows installation disc.
First Boot From the Windows Install Disc
Click on repair your computer
Choose the installation and click the Next button.
On the System Recovery Option click on the command prompt.
Repair the Master Boot Record
To restore the master boot record type:
To write the new boot sector on system partition type:
In this way we can fix the “BOOTMGR is missing” error while trying to boot up Windows 7 .