Fixing registry problems via system restore when windows won't boot.
Everybody knows about system restore, how you can use it to restore your system back to a particular date when all was well. What happens when windows does not boot, because of a problem with the registry? Everybody’s first thought is either performing a repair installation of windows or formatting and reinstalling. Before going that drastic there is one Hail Mary you can attempt before giving up all hope. To do this you need a copy of bartpe (a version of windows that you can boot off a CD.
http://www.nu2.nu/pebuilder (you can use this free software to make your own)
System restore stores all of the restore points in the root of C: in a folder called “System Volume Information” (You have to tell windows to show Protected Operating system files).
If you open that folder you will see a folder called “_restore (and then a bunch of numbers)”. All your machines restore points are stored there. The restore points all share a common name, the letters RP and then a number (example RP143). The numbers themselves don’t really tell you when that restore point was created, but the time stamp does. So it’s best to view by details and arrange by date. So you pick a RP folder corresponding by the date you want to go back to and open it up. Every restore point has a “Snapshot” folder. This folder contains a backup of the system registry the day the restore point was created.
All the registry backups start with the name _Registry_User followed by the name of the registry file. Example _REGISTRY_MACHINE_SYSTEM. (all that file needs is a little rename love’n and it will be as good as new).
Windows stores all of its registry entries in c:\windows(or winnt)\system32\config. So it’s best to backup that folder up before making any changes. After that’s done it’s a good idea to rename the current registry entries to something else, like system to systemold. Now return to your “Snapshot” directory and copy all backed up registry entries and paste them in c:\windows(or winnt)\system32\config.
All it takes now is just a little renaming. Let’s take system for example. The backup of the system registry file is called _REGISTRY_MACHINE_SYSTEM. Right click it and rename it to what the old file was called. In this case the file was called just system with no file extension. The same goes for the rest of the registry files. The most common registry files to get you back up and running are, System,Software,Security,SAM and Default. I usually just restore all of them.
Once complete reboot your machine. If all goes well the once unbootable windows installation should come back to life, if all that was wrong was the registry. This has worked on more than one occasion, when the fate of a windows install was looking pretty bleak.
Edited by warwagon, 14 June 2012 - 22:31.