Disappearing Files after XP Reinstallation

Scenario:

After re-installing Win XP operating system on drive “C”. After re-installation, I was able to see all the files on “C:”, EXCEPT that ALL of the files previously saved under “My Documents” (Documents and Settings > My Documents) had been replaced by a new set of ‘default’ folders. For example, Word documents saved in “My Documents” disappeared.

Win XP OS had also been installed on another drive “D”.

QUESTION:

Would re-installing XP OS cause all those files in “My Documents” to be replaced? How do I recover these files?