Mavericks HDD swapped while in sleep mode is now unreadable
Oh man - that's a bad situation. All is certainly not lost.

I would start by calling one or two data recovery services to get a quote from them. Once you have that, consider you could pay $99 for software that would look over the drive and offer to recover files.

With those estimates, you can decide if your time and photos are worth further efforts to salvage or if you just write them off and erase the drive to start over.