Over- or Re-Writing WinXP System Files

[jeanpave]

If I'm not mistaken, I think there is a method to insert the CD originally used to install Windows XP on a PC and overwrite/rewrite all the system files (that the CD can offer) without messing up anything else saved on that OS (prior to doing/attempting this).

For example, if 2 years ago, a photo was saved in a folder created 3 years ago (somewhere on the Desktop or in 'My Documents' for instance), even if the CD rewrites the entire Windows folder, and Program Files, and so on, that photo and folder are still safely preserved.
Also, if 1 year ago, let's say, a program was installed, called, I don't know, CCleaner, or something, that one should still remain in Program Files, and its shortcut on the Desktop, and so on, just as if no installation had ever been performed or modified.

It's clear what I want, right?

Don't want to format anything, erase anything, mess with the current boot process. No fresh installation is needed.
No messing around with the registry is wanted, either, unless there is no alternative. Want basically the same programs that start with Windows right now to remain at the same level of functionality.

Can anybody, please, post a step-by-step guide, beginning with the insertion of the Windows XP CD into the appropriate tray, making it as simple to follow as possible, as if for a newbie?
Thanks to everyone who helps, very much.

P.S. A Google search revealed methods of checking for corrupt system files, such as "Sfc.exe". However, the process I am trying to achieve needs to involve the original Windows XP CD 100% and to overwrite all the system files (almost as if a fresh installation) but leave everything else (e.g. personalized files, boot sector, etc.) as they are/were. Surely, this is possible with the CD, unless I remember wrongly.

[usually_quiet]

Do you mean a repair installation? A search engine should be able to find quite a few guides explaining what to do.

[Budman1]

Believe that SFC does this (https://support.microsoft.com/en-us/help/929833/use-the-system-file-checker-tool-to-re...d-system-files) it scans and replaces any missing or damaged from your CD or a folder on your PC.

[pandy]

Usually not as Windows Update may replace/modify some system files with newer version - mismatch between file versions and register may lead o BSOD. You should use only tools provided by Microsoft and never overwrite manually your system files especially from old disc.

[teodz1984]

http://michaelstevenstech.com/XPrepairinstall.htm

But it is not as good as a fressh installl

[sophisticles]

P.S. A Google search revealed methods of checking for corrupt system files, such as "Sfc.exe". However, the process I am trying to achieve needs to involve the original Windows XP CD 100% and to overwrite all the system files (almost as if a fresh installation) but leave everything else (e.g. personalized files, boot sector, etc.) as they are/were. Surely, this is possible with the CD, unless I remember wrongly.

SFC is what you're looking for:

https://www.lifewire.com/how-to-use-sfc-scannow-to-repair-windows-system-files-2626161

Tip: In some situations, most often in Windows XP and Windows 2000, you may also need access to your original Windows installation CD or DVD at some point during this process.

Open a Command Prompt, type in sfc /scannow and wait for it to be done, in pre-Vista Windows you may be prompted for the install media.

[Nelson37]

What you want is a Repair install, the second Repair option, the first is for command line access, SFC is NOT sufficient for the task, it will NOT re-write all or even very many system files, only those missing or severely corrupted. Should keep programs, and definitely any and all data files, pix, docs, etc. May need to run updates for some programs, ideally have latest service pack slip-streamed onto the CD, or at least use a modern CD.