Realizing mid reinstall that I'm losing my data. Help!

I was trying to reset my password and ended up accidentally reinstalling my operating system. After doing so, I realized that I was probably losing my data, so I tried to stop the process by selecting quit. I was eventually prompted to pick a startup location, chose the hard drive option and then got the dialog box "You can't change the startup disk to the selected disk, the bless tool was unable to set the current boot disk." I've just left the dialog box up there, and my computer is plugged in. I'm just wondering if there's any hope in this situation. I have a bunch of photos on there that haven't been backed up (I know, dumb!!) I made a genius appointment, but I'm anxious to hear if you think I may be able to recover my photos. Thanks!