How to fix Windows 7/ Win8 boot problem with BCDEDIT

1. At the Command Prompt, type C:, then dir to make sure the C: drive has Windows folder.

   X:\Sources>C:
   
   C:\>dir
    Volume in drive C has no label.
    Volume Serial Number is 08B5-DD80
   
    Directory of C:\
   
   06/10/2009   01:42 PM                24 autoexec.bat
   06/10/2009   01:42 PM                10 config.sys
   04/09/2013   03:07 AM    <DIR>          Documents
   07/13/2009   06:37 PM    <DIR>          PerfLogs
   04/28/2013   12:59 PM    <DIR>          PortableApps
   04/27/2013   01:12 PM    <DIR>          Program Files
   10/14/2012   12:42 PM           148,376 Start.exe
   04/08/2013   09:39 AM    <DIR>          Users
   04/23/2013   09:02 AM    <DIR>          Windows
                   3 Files(s)       148,410 bytes
                   6 Dir(s)  24,614,199,296 bytes free

   If the C: drive doesn't have "Windows" folder, keep changing to the next letter drive (D:, E:, etc.) until you find a drive that has. Note the letter of this drive (C: in this case).
2. Type "bcdedit /store C:\Boot\BCD /enum" to show boot entries.

   C:\>bcdedit /store C:\Boot\BCD /enum
   
   Windows Boot Manager
   --------------------
   identifier              {bootmgr}
   device                  unknown
   description             Windows Boot Manager
   locale                  en-US
   inherit                 {globalsettings}
   default                 {default}
   resumeobject            {aaefde36-a035-11e2-85f9-d08a24bd2bde}
   displayorder            {default}
   toolsdisplayorder       {memdiag}
   timeout                 30
   
   Windows Boot Loader
   -------------------
   identifier              {default}
   device                  unknown
   path                    \Windows\system32\winload.exe
   description             Windows 7
   locale                  en-US
   inherit                 {bootloadersettings}
   recoverysequence        {aaefde38-a035-11e2-85f9-d08a24bd2bde}
   recoveryenabled         Yes
   osdevice                unknown
   systemroot              \Windows
   resumeobject            {aaefde36-a035-11e2-85f9-d08a24bd2bde}
   nx                      OptIn

   We should find the lines that have "unknown" values, and correct them by setting the value to "partition=C:" — or whatever drive has "Windows" folder.
3. To fix the lines with "unknown" values, use bcdedit as follows.

   bcdedit /store C:\Boot\BCD /set {bootmgr} device partition=C:
   bcdedit /store C:\Boot\BCD /set {default} device partition=C:
   bcdedit /store C:\Boot\BCD /set {default} osdevice partition=C:

4. To verify that corrections were made to the Windows 7 boot configuration, run bcdedit again.

   C:\>bcdedit /store C:\Boot\BCD /enum
   
   Windows Boot Manager
   --------------------
   identifier              {bootmgr}
   device                  partition=C:
   description             Windows Boot Manager
   locale                  en-US
   inherit                 {globalsettings}
   default                 {default}
   resumeobject            {aaefde36-a035-11e2-85f9-d08a24bd2bde}
   displayorder            {default}
   toolsdisplayorder       {memdiag}
   timeout                 30
   
   Windows Boot Loader
   -------------------
   identifier              {default}
   device                  partition=C:
   path                    \Windows\system32\winload.exe
   description             Windows 7
   locale                  en-US
   inherit                 {bootloadersettings}
   recoverysequence        {aaefde38-a035-11e2-85f9-d08a24bd2bde}
   recoveryenabled         Yes
   osdevice                partition=C:
   systemroot              \Windows
   resumeobject            {aaefde36-a035-11e2-85f9-d08a24bd2bde}
   nx                      OptIn

   You can see that "partition=C:" values appear on lines that previously had "unknown" values.
5. Windows will now boot normally. Close all windows and restart the computer.