Mac hangs at boot .. unmounted HDD?

[calcalcal]

hey folks

the other day i was mucking around on my macbook (10.5, 2 gigs of ram, 2.4)
and i realised that in finder/pathfinder that my one and only harddrive's
eject button was missing... i dont konw wat caused this as my mac has been
continually been on for a few days.. (using sleep instead of shutdown)
but after noticing this i tried to install a few dmgs : "no mountable file systems"

so i tried to reboot and but it just hangs on the grey screen with the initial spinning wheel... im quite new to mac so i dont konw how to boot up with the
disc and do stuff like that..

but i did read on another thread to boot with ctrl S and then type in /sbin/fsck -fy
it said the hdd was ok .. i just think i need to mount it again??????

or is that just crazy talk ???

any help would be much appreciated

 

[calcalcal]

i forgot to mention that i did try the app "disk utility" when it was on (before i rebooted) and i did repair the permissions and the hdd was all good ...
also i tried to remount it from that program but it was grayed out and i couldnt!