UNMOUNTABLE_BOOT_DISK - Please Help

Ok, so I tried to boot up my computer last night and a blue screen popped up with a "UNMOUNTABLE_BOOT_DISK" error. It said to restart and if that didn't work to hit F8 and boot in Safe Mode. I tried that and then it just start listing system32/drivers and then continued onto the same blue screen. I'm baffled as to what to do here. I'm currently looking for my disks that came with my laptop (Dell). Any advice would be much appreciated.