Lost all the ringtones (non-music) that I created myself

Lost all the ringtones (non-music) that I created myself in a music studio a couple of years ago, both from my iPhone & from iTunes.

I still have the original files in garageband, but can't add them back to iTunes again.

There is no 'Tones' folder in my iTunes media folder.

What do I need to do to sync them back, & to prevent this from happening again in future?