'Nincs mit tenni' literally means 'Nothing can be done about that', there is no solution for this problem.

I would say, "there is nothing to do". (or to be done), nothing doing.

Did you lose your money (on a transaction or bid or something similar)? You can't change it. I hope it was helpful.

Yes, there is nothing you could do about it. Similar: Ez van, ezt kell szeretni. -> That's all there is to it, we will have do with this.