How to Restore MBR Without a CD
Windows installation CDs and DVDs have a number of system repair and recovery tools included that can get almost any computer back on its feet after a bad crash or faulty operating system installation. One very common problem that comes up when installing a second operating system is a corrupted Master Boot Record, or MBR. Windows System Recovery has tools that can fix a corrupted MBR, but if you don't have an installation CD or CD drive to put it in, you're going to need to copy the recovery materials to another medium, like a USB drive. If your MBR is corrupted, you probably don't have access to your Windows installation, so you'll have to follow most of these steps on another computer.
Things You'll Need
- 1GB USB drive
- Second computer running Windows 7
Insert the USB drive into another computer and run a command prompt window by typing "cmd" into the search box of the "Start" menu and hitting "Enter."
Enter "mkdir X:\boot," and "mkdir X:\boot\sources" where X is the drive letter of your USB drive.
Type "cd" and press the "Tab" key once, then hit "Enter."
Enter "xcopy /H boot.sdi X:\boot," "xcopy /H Winre.wim X:\sources\boot.wim," "xcopy /H c:\windows\boot\dvd\pcat\bcd X:\boot," "xcopy /H c:\windows\boot\dvd\pcat\en-US\bootfix.bin X:\boot," and "xcopy /H c:\windows\boot\pcat\bootmgr X:\" to copy the necessary files to the USB drive.
Enter "attrib -r -s -h /s X:\*"
Enter "diskpart" to run the DiskPart program, then enter "list disk." The window lists the drives connected to your computer. Find your USB drive in the list and enter "select disk X", where X is the letter of your USB drive. Enter "list partition" to see the partitions on the drive and then "select partition X," where X is the number of the partition listed.
Insert the USB drive into your computer and turn the computer on. Allow it to boot from the USB drive. You may have to set your USB drive as a primary boot drive in the computer's BIOS first. Enter your computer's BIOS (by tapping Delete or F2 during bootup, on most computers), then put your USB drive at the top of the "Startup" list.
Go to the "Startup Repair" option in the "System Recovery Options" window. The "Startup Repair" process should correct your Master Boot Record and allow Windows to boot normally again. You will probably lose access to any other operating systems installed on your computer, though, since this recovery option is only designed to get Windows working again.