Scared me there for a second. I thought that you may have had your drive formatted for FAT32. I just tried the program without selecting a drive and got the same message. Right under the "file" tab is a dropdown where you select the drive. I am guessing that you only have a C: Drive so select that. If you have additional drives then search them as well.

I hope this works for you. Really feel for you losing all that data. May want to make and investment into a external USB drive to back up your runtime folders for the future.