Re: Complete loss of fingernail
The root of the nail is deeper than you might think. The nail plate probably just came loose from under the cuticle. The matrix would continue to develop nail plate cells unless it had been surgically removed. When the new nail plate begins to appear, it might be slightly damaged or ridged, but as the matrix adn the nail bed heal, it will grow in more normal.
It is better if you would keep the exposed nail bed clean and dry. Apply a small amount of antibacterial ointment and wrap the finger with plain gauze, using the ends of the gauze to tie it onto the finger. Bandaids tend to hold more moisture which can slow the healing time.