If you see just a blinking cursor then this may indicate a disk problem.
I would first check the integrity of the disk usig MHDD just to be sure, I wrote some instructions here:
http://www.daemonforums.org/showpost...64&postcount=4
Assuming the disk is OK, you can download & burn the
livefs image and inspect the disk.
I can't tell you what will turn up here, but you can try to read the partition table (with
fdisk(8)),
disklabel(8) and filesystem (with
mount(8)).
You can also reinstall the boot loader with
boot0cfg(8) if need be.
But first:
check your disk.
especially if it holds important data as you mentioned.