can't help it; can do nothing about it
Nobody can do anything about it.
Je sais que nul n'y peut rien si la nature ne nous vient pas en aide.
I know that no one can do anything about it if nature doesn’t come to our aid.
— Guerre et Paix (1968)
Tom n'y peut rien.
Tom can't do anything about it.
S'il n'écoute pas, je n'y peut rien.
If he doesn't listen, there's nothing I can do about it.
— The Legend of Bhagat Singh (2002)