Windows Registry has zero tolerance policy regarding any unwanted change done to it. You cannot undo the change, once you made it. The only method to revert your PC back to the way it was before you made the change is to re-edit the Windows Registry manually. Windows registry is complicated and if you are not computer savvy, this is not the best solution for you. Therefore, it is essential to take necessary precautions prior to editing Registry. Before modifying windows registry, you are advised to take back up.
If you are Windows XP user then you have number of ways to take back-up. You can take back-up of entire registry or just a part of registry as required. Using third party Registry Cleaner and PC optimizer tools to create backup is much helpful. Below are discussed few methods for your understanding.
XP operating system is equipped with disaster recovery System Restore feature. Users can use this feature to create a screenshot of Registry before modifying it. If you face any difficulties while operating your system, you can revert your system settings. In cases this method is not much successful because it removes the screenshots taken a long time ago to save system space.
To take an entire backup of Windows registry you can also use NT backup utility. This utility would enable you to create the back up of registry, COM + Class registration database and boot files.
If you cannot do that manually then you should search for third party software "Registry Cleaner and PC Optimizer" from Internet. The main objective is to scan the registry and remove any obsolete and unwanted date from registry. So, Registry Cleaner and PC Optimizer tool enables us to perform all these tasks quickly. Advanced Registry Cleaners also provide registry backup feature that you can use before modifying it.
To create a Registry Backup, experts recommend RegInOut (registry cleaner and pc optimizer) tool that not only creates backup but also fixes internet registry errors and common PC problems.