Thanks for your reply. That Rebistry entry you mention "no control panel................." is really and truly not there.
Nor mine.
Try this:
Create a new folder on your Desktop and name it Tempcpl.
Open Windows file search (ensure you have enabled a search for hidden system files and folders).
Search on your C drive for
*.cpl
A window will open displaying all .cpl files.
Move all the files that are listed in the Windows\system32 folder to the Tempcpl folder previously created.
Now see if Control Panel will open.
If it does, XP should have recreate the removed files.
Note, XP will not create those cpl files created by software such as Java, so move those missing ones required back into the the system 32 folder and check that Control Panel still opens. If not, then those files moved may be corrupt.
If all is now functioning as it should, delete the Tempcpl folder.
exo