If it is not possible to boot in safe mode and "last known good
configuration" is damaged then you can restore registry files from a
full registry backup created by Registry First Aid or from a
system backup created before Registry First Aid registry
scan.
In this case you need either another copy
of Windows installed or Recovery Console installed. Read install Recovery Console and how to use
it topic.
There may be several variants to boot into another
copy of Windows (at least Windows XP is required):
- a second operating system installed on that machine;
- or install a new OS into another folder (not
C:\Windows originally) or another partition;
- or connect hard drive to a machine with Windows installed;
- or make a boot CD or flash drive with Windows or another OS with support of NTFS.
The better and easier choice is using a boot device.
There are a lot of bootable images in the Internet especially designed for Windows recovery.
Manual restore registry files from a full registry backup created by Registry First Aid before registry scan
Manual restore registry files from a system backup created before Registry First Aid registry scan
Manual restore registry to the state that was just after installing Windows
Note: If none of this helped you then your problem was coming not from
registry but from damaged system files. You may need to re-install your
system to restore system files.