BOOTMGR—short for —is a small but critical system file that manages the startup process in Windows Vista, Windows 7, and later operating systems (it replaces the older NTLDR used in Windows XP and earlier versions).
Insert your Windows 7 installation DVD or Recovery USB and restart the computer. Step 2: Press any key to boot from the media. Step 3: Select your Language and Keyboard layout , then click Next . Step 4: Click "Repair your computer" (bottom left corner – do not click "Install now"). Step 5: The system will scan for installed Windows 7 installations. Select your operating system and click Next . Step 6: In the System Recovery Options menu, choose Startup Repair . windows 7 bootmgr download