Well, assuming you didn't actually wipe the Windows partition, then is it possible you had multiple drivers and somehow your actual bootsector and boot partition was on the drive you did wipe?
So you basically, hopefully, just need a need a new boot sector.
It used to be that live Linux disc were actually good at recreating them. Or more precisely a Linux installation to an empty partition would also create a new bootsector, GRUB, etc. and an entry for you Windows.
However, I think your first step should be to try a Windows installation disc and try and get that to fix the bootsector (so don't run the installer).