I would add that while Sauron's original body was destroyed during Ar-Pharazôn's attempt to enter Valinor (when Númenor was destroyed), his spirit survived and fled back to Middle-earth. While it is not exactly described how Sauron was, I assume that he was very likely like the Nazgûl: When swept down by the flood or killed by Merry/Éowyn they left no physical body.
Sauron is likely like his servants more living in the Unseen world and needs magic to give his spirit presence; it is explicitly mentioned in the first book that Sauron gave the Nazgûl their garment to give their normal spirits a form to act in the material world. So as Daft said, he would have garb for himself enabling him to put the ring again on his finger.