Your fingernails are already dead. Same as hair.

I believe the reason for the whiteness is the nail pulling away from your nail bed. You probably caught your nail on something or used it to open something. Broke whatever glue type thing is going on that sticks out nails and fingers together. It should disappear as your nail grows out.

If you check you should find that all your nails are white at the end. And they turn white right where they stop being stuck to your finger. You might even be able to poke some areas under your nail to pull your finger away a little bit and see what's usually pink go a little bit more white a see through where your nail isn't quite stuck down anymore but is still smushed right up against your finger most of the time. Or you might see the white go a bit less white and blend in more with the rest of your nail if you push your finger up to it more.