Go to the console and watch for drive errors. If you are getting data errors, a recovery disk may work.
It may not be the drive. It might be the ATA controller. Boot into the BIOS and check your hard drive configuration. If the BIOS doesn’t “see” the drive, you’re probably up a creek. If you can still see the drive, the boot sectors probably got clobbered and a rescue disk will probably work.
If the machine doesn’t see the drive at all, you can try some of the old-school tricks like putting the drive in the freezer and restarting it once it’s cold. Note that this usually only works once, so have a good hard drive available to get your data. You can also try power cycling the machine a few times to see if you get one more boot cycle out of it. Either way, the drive should be considered toast and will need to be replaced ASAP, preferably before you start anything that looks like recovery.