In Windows XP, click the Start button and then click Run .
Step 2: In the search box or Run window, type the following:
regedit
and then press Enter .
Note: Depending on the version of Windows and how it is configured, users may see the User Account Control dialog box to confirm opening the Registry Editor.
Step 3: Registry Editor appears. If you have used Registry Editor before, it will open the same location you worked on last time. In this case, if you don't want to work with keys or values in that location, just continue to minimize the registry keys until you see the hive registry.
Tip: You can minimize or expand the registry keys by clicking or tapping the small icon > next to the key. In Windows XP, the + symbol will be replaced for the> icon.
Step 4: Now users can make any registry changes.
Note : Back up regisrtry before making any changes in case something goes wrong.
See also: Clean the Registry effectively
See also: Registry disabled and how to fix it