The "BOOTMGR is missing" error in Windows 7 usually indicates a damaged boot sector, corrupted boot configuration data (BCD), or incorrect BIOS settings . While you cannot "download" a standalone
Once you have the USB/DVD, boot from it. You now have safe access to the original BOOTMGR file on the media: X:\bootmgr (where X is your DVD drive letter). windows 7 bootmgr download