Hi,
Thank you for posting your question in the Microsoft Community Forums.
Based on the information, you are facing issues to access the Helpcenter and when trying to fix the issue by modifying the registry, it seems the whole registry location "HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows/CurrentVersion/App Paths" is missing.
The issue is a bit unclear. It would be helpful if you could reply to the questions to assist you better.
- Are you able to navigate to the location "HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows/CurrentVersion/App Paths"?
- If you are able to navigate, are you able to view the HelpCtr.exe?
- Do you remember making any changes to the computer prior to accessing Helpcenter issue?
Please provide us with more information on the issue, so that we can help you further to fix the issue.
Meanwhile you may try performing a system restore and check if it helps.
How to restore Windows XP to a previous state
Note: When you perform System Restore to restore the computer to previous state, programs and updates you installed are removed.
For further information, refer to the article:
You cannot open Help and Support Center in Windows XP
Unable to load Windows Help and Support
Important: The above mentioned articles tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs.
For more information about how to back up and restore the registry, follow the steps from the below link:
How to back up and restore the registry in Windows XP
Let us know if you need further assistance with Windows related issues. We will be happy to help.