Your probably running Tiger,if thats the case then your'll need the the install disks that came with your machine,backup all your stuff boot from the CD you can either do a
do a archive & install or a clean install .Bootcamp beta expired on Tiger when Apple bought out Leopard,so if you ever need bootcamp again you would have to either upgrade
to Leopard or i think there is away were you turn back the clocks somehow
The only other way would be to boot from the CD go into disk utility and see if you can restore the partition from there