I do not know what happened, or how lucky you were.
I suggest you only LOOK at Drive Wiper, taking no other actions.
Against Wipe you get the choices of "Free Space Only" or "Entire Drive (All data will be erased)"
Against Security is the Overwrite control which you set to 3 passes
Against Drives are check-boxes for all the drive letters that can be seen.
Do not now press the Wipe button.
When you previously pressed the Wipe button it should have either proceeded to Wipe Free Space,
OR if you had selected "Entire ..." then before action it should have required you to type the word ERASE.
If your Windows partition, probably shown as (C:), had been checked,
then CCleaner is designed to avoid erasing any data or doing any harm, though it may wipe free space.
ANY other Drive letters will, if the box was checked, receive "appropriate" treatment.
You should use Windows Explorer to look at any other drive letters.
If they contain no files they were probably erased.
If Windows was pre-installed there is a high possibility that you had a "recovery" partition instead of a Windows Installation Disc.
When Windows self-destructs ( a habit I fear it will never shake off ) then the Recovery partition should make it "good as new".
H.P. use D:\ for their recovery partition, and that would be a valid target for CCleaner to ERASE.
Alternative suppliers could have chosen to refrain from allocating a drive letter - in which case CCleaner would not have seen or touched it.
A Windows Installation Disc is, in my view, better than a "recovery" partition because it does not include unwanted trial software.
If you have no Installation Disc, and if there is no Recovery Partition, you may need to get or make an installation Disc.
I suggest you accept Hazelnut's advice - creating a System Repair Disc and making system images.
There have never been legal sources for a XP download.
I believe Windows 7 Installation downloads are free and legal,
but I will leave it for a moderator to answer if you need a link.