Resolve blue screen error using command prompt in VISTA/WINDOWS7!!
The Blue Screen Of Death (also known as BSoD or bluescreen), known officially as a Stop Error  or a bug check, is the error screen displayed by the Microsoft Windows family of operating systems upon encountering a critical error, of a non-recoverable nature, that causes the system to "crash." The term is named after the color of the screen generated by the error.
Stop errors are usually hardware or driver related, causing the computer to stop responding in order to prevent damage to the hardware, whereupon, in the latest versions of Windows, the screen presents information for diagnostic purposes that was collected as the operating system performed a bug check.
The very first thing that tricks into ones mind while reading the TITLE of the post is "Why to use COMMAND PROMPT".Just format or use recovery disk to repair the OS.
I would like to say that solving the problem using command prompt is challenging/ tracky and also fast..So lets once try for It!!
I recently encountered a FATAL error while defragmenting registry with system registry cleaners.Once the defragmenting was over I was asked to REBOOT the computer which i willingly did BUT the system crashed showing the blue screen error.As if this was not enough I had also disabled the SYSTEM PROTECTION property of SYSTEM drive(DRIVE containing operating system) as a result of which i was not able to restore my system to any of the previous dates.
If you are not willing to format your computer and also not to loose your data ot lost the original CD(or don't have one) then simply follow the following steps :
STEP 1 : Select the option system repair and recovery (recommended wont detect errors, and if it does it will say that they can't be fixed automatically so what we need to do is go into advanced options so that we can get to cmd prompt.
STEP 2 : Open the command prompt.
STEP 3 : TYPE 'DISKPART'(without the quotes).
Now when you will get the prompt as DISKPART>
STEP 4 : TYPE 'SELECT VOLUME 1'
STEP 5 : TYPE 'REMOVE LETTER C'
STEP 6 : TYPE 'SELECT VOLUME 2'
STEP 7 : TYPE 'ASSIGN LETTER C'
STEP 8 : TYPE 'SELECT VOLUME 1'
STEP 9 : TYPE 'ASSIGN LETTER D'
STEP 10: TYPE 'EXIT'
STEP 11(optional): chkdsk D: /F/R (for 5 level check disk to check disk integrity)
STEP 12:: TYPE 'REGEDIT'
The regedit window would pop up.
STEP 13: Select file -> import from the window.One good thing about Vista and windows7 is that we can copy/cut/move files through any of these windows
STEP 14: Go to "\windows\system32\config" in the popup window.
STEP 15: Rename the files SAM, SOFTWARE and SYSTEM by adding the extension ".abc" (just an example)
STEP 16: Now go to "\windows\system32\config\regback" in the popup window.
STEP 17: Copy the same files (SAM, SOFTWARE and SYSTEM) to "\windows\system32\config" from "\windows\system32\config\regback"
STEP 18: REPEAT step 3 to step 10 to revert the drive names.
STEP 19: TYPE "rstrui.exe"
The result is that the drive letter changing fixes the confusion in your system which doesn't allow you to do system restore because of the "system protection" problem, and the file replacement puts in a good registry so that we can do the system restore without errors.!!