Fix Deleted SAM File Causing Windows Vista Unable to Boot Error

Windows NT and XP operating system stores user information in the Security accounts Manager (SAM)
database. Windows Vista also carries SAM and SYSTEM files, although the LM hashes for the encrypted passwords has been disabled. However, the SAM file is still an important file. If the SAM file is accidentally deleted away, the computer will be unable to startup.

In Windows Vista, SAM file is located in %SystemRoot%\System32\config\ folder. If the C:\Windows\System32\config\SAM file is deleted, the PC will stop halt and automatically reboot during system startup, right after user seeing the first sign of mice pointer. The Windows Vista PC will continue to reboot in endless infinite loop, causing system unusable. Even trying to get into Safe Mode will fail with automatic restart.

If the SAM file has been removed or deleted, either by intention or accident, Windows Vista has a backup copy of it that can be used to restore or recover the SAM file. It’s practically impossible to copy the SAM file from another system because it may contains the sensitive secret user password data. The backup or second copy of SAM file is located in C:\Windows\System32\config\RegBack folder.

To to get back the SAM file, simply copy the file from C:\Windows\System32\config\RegBack\SAM file. However, the default system SAM file has the size of 256KB, while the backup copy has only 64KB. Although file size is different, however it’s enough to allow system to boot into desktop without the need to reinstalling Windows Vista.

Beside, to copy the SAM file back into its original location, user may have to use Recovery Console Environment or boot into another system which allows access to NTFS filesystem of Vista system drive.