Ringtones are not included in a device's backup (no iTunes download is), an iTunes restore would look to pick them up from the Tones part of your iTunes library.
If you don't have copies of them in your iTunes library or on your backup of your downloads/library, then if they are still in your country's store (and you haven't changed counties since buying them), then you could try contacting iTunes Support and see if they will grant you a redownload : http://www.apple.com/support/itunes/contact/
If not already doing so then you should be keeping and maintaining a backup copy of all of your downloads. Tones and audiobooks are one-time only downloads, other items are only redownloadable whilst they remain in the store and you don't move countries.