If you had to wipe your hard drive, it would be difficult to recover anything from it. That's why you need backups of everything. If you have backups, just restore them. If you don't have backups, well, now you know why you need backups of your catalog file and all photos and anything else you don't want to lose.
It depends on how you wiped your drive. Depending on how you did it, only the directory was erased and the data can be found with drive recovery software. Some are free, although there is a small charge for most of them (~$30). You can usually download a trial version that shows if it will work and you have to pay to be able to save the found files. Use Google to search for the software. Different programs work differently and can find different things.
John, if the operating system and software have been re-installed, the likelihood of restoring files from before the wipe is low. Not impossible, but in my opinion unlikely.