$ sudo fdisk -l /dev/hdX
For ide harddisk, or
$ sudo fdisk -l /dev/sdX
for sata harddisk. Where X is either a, b, c, d, depending on how many hd's you have. If one, use 'a' (hda or sda).
What does this command tells you? Please, put the output here.
My guess is, giving the scenario, you used ubuntu's default partition scheme. The sad part is, if it did what I think it did, Windows is long gone. I have no idea (don't even know if it is possible) to recover lost data if it formatted the whole hd and used it's partitioning scheme.