Do you use grub?
Did you follow these steps
here, the first method under "Linux before Vista" or what else did you do after reinstalling Windows?
If you reinstall grub as described there, you probably want to put it in the /boot partition of Mageia, if you have one, or in / of Mageia otherwise.
I guess you'll need a Mageia live (or rescue; don't know which one that is) medium to repair your installation. With that, you can chroot into the Mageia installation on your harddisk and perform the grub repair as described in the EasyBCD doc.