HELP! Stuck in OS9

OK- I'm having major problems here.
I'm just playing around on an old eMac, running with OS X. I was mucking around and rebooted in an OS 9 that was on there. When I rebooted it, it tried to install OS 9 or something, I turned it off (stupidly enough) in hope of just rebooting in OS X, but now i'm stuck with the folder with a flashing question mark.
I don't have any boot disks handy, I've tried holding the option key down and all i get is two arrows, one in the shape of a circle, and even when i press either of those nothing happens.
I've tried resetting the PRAM and nothing seems to be working- i'm about the explode with frustration. Any suggestions?