First of all, you'll want to make sure you uninstalled the actual game and not just deleted the folders. In your Feral Heart Folder there should be a program named "uninstall.exe". Run that and let it do it's magic. When it's finished, it should successfully wipe Feral Heart off your computer. The folders will still be there, but they will be empty and ineffective so you can just manually delete them if you like. To reinstall, just find the FHSetup.exe in your downloads, or re-download from the website here and run that to get everything back. It will automatically create new folders for you in your local disk (C: Drive) Make sure you create a copy of anything you don't want to lose, such as markings, presets, or items, so you can just toss those back into the folders when you re-install.
Also, if you no longer have the unistall.exe in your FH folder because it seems like you deleted most of the files in the FH folder, go into your trash bin on your computer and try to find in restore it, that way you can properly uninstall. Hope it works! :3