You'll need to recreate the partition table. Do you have a computer that you can install Linux on? If not, then you can use a "Live CD" version.
Once you get into Linux, you'll re-create the partition table using gparted or fdisk.
Alternatively, you may want to try testdisk, which can recover a partition table. There is a version that'll run under windows.
http://www.cgsecurity.org/wiki/TestDisk