it's no use
It is hopeless; there is no point or reason (in doing something). It's no use, I just can't figure out what's wrong with the car. It's no use asking Dave about the numbers—he can't even balance his own check book.
no use, it's
1. It's impossible; it can't succeed. For example, It's no use; these pieces just don't fit. [c. 1800]
2. Also, it's no use to man or beast. It's worthless, it serves no purpose, as in This car is so old it's no use to man or beast. Also see have no use for.