To Backup/Restore ur Registry

1.Open command prompt(cmd), type the following

Attrib -s -r -h C:\Windows\System.dat , press enter
Attrib -s -r -h C:\Windows\User.dat, press enter

To Make the backup copies type:
copy C:\Windows\System.dat C:\Windows\System.000 , press enter
copy C:\Windows\User.dat C:\Windows\user.000, press enter

To Restore the Registry Type
copy C:\Windows\System.000 C:\Windows\System.dat , press enter
copy C:\Windows\User.000 C:\Windows\user.dat , press enter