Informal:
* "Tant pis!" - This is the most common and direct translation, similar to "tough luck!" or "too bad!"
* "Bah!" - This is a more casual and dismissive expression, similar to "whatever!" or "so what!"
More formal:
* "C'est comme ça." - This literally means "it's like that" and implies acceptance of the situation.
* "Que voulez-vous?" - This literally means "what do you want?" and suggests that there's nothing you can do about it.
Other options:
* "On ne peut rien y faire." - This means "there's nothing we can do about it."
* "Ce n'est pas grave." - This means "it's not serious" or "it doesn't matter."
The best option will depend on the context and the tone you want to convey.