On the installation screen, press Shift+F10 to open a command prompt. (In our case, it was the Windows Server 2012 R2 install media). You can make sure that the System Reserved partition is missing by booting from any Windows boot/installation media ( USB flash drive or DVD). These steps will help you fix Windows boot after deleting a System Reserved partition. If other partitions prevent you from shrinking/ extending the Windows volume, you can restore the bootloader configuration and place it on the partition where Windows is installed. Windows Can’t Boot after Accidentally Deleted System Reserved Partition However, in most cases, it is easier to move the bootmgr configuration to the Windows system partition (this is described in the next section of the article). Now you can place the Windows bootloader files on the new partition:
