If it is completely gone, you can lightly wrap and pad the affected bed and use a antimicrobial agent (like bactine, or neosporian) to keep it moist until it heals.
Bandage it up. If your toenail is completely detached from your toe there is nothing for you to do but wait for it to grow back. Make sure nothing irritates it and keep it clean.
Nothing. If the toe is irritated when wearing shoes and socks, apply a bandaid. With time, the nail will grow back. Takes about 8 weeks for new nail to grow.
