Recover stupid mistake

[Mike Martin]

Hi when I was trying (and failing) to get a bootable pen-drive, with
the F13 live image I accidentally did the following

dd if=/dev/zero of=/dev/sdb bs=512 count=1

which returned nearly immediately and now I have no data on the disk.

The disk is 750 gig , of which about 400 is used. I am hoping that
only the partition table is gone, if not is there any way to recover
from my disaster