Toenails do grow back, but how well toenails grow back depends upon where they were broken. Nail growth occurs in the lunula, the white half-moon shape at the bottom of the nail.
If the lunula is damaged, a toenail still grows back, but nail growth is permanently changed. These changes can include the nail having a bumpy texture or the nail becoming much thicker.
Nail loss can be due to a trauma or a fungal infection, which can cause the nail to become detached from the nail bed. A detached toenail appears white in the area that has separated from the nail bed.