dd problem

Hi,
  i wanted to make a boot floppy for my linux box.
Inserted the floppy and typed 
dd if=/boot/vmlinuz-2.4.10 of=/dev/hda1 bs=512.
instead of typing of=/dev/fd0 and i wrongly typed
of=/dev/hda1. (/dev/hda1 is the partition where my linux is installed).
After the command got exectued, i am not able to see
any thing in my directories. Like when i type 'ls' i am not able to see any
files. 
  Please let me know how i can revert back to the
original position.

Any help is greatly appreciated.
Thanks,
sreedhar.