“At this point, I don't think there's much we can do about it.”
You are almost finished with a major project at work when a coworker from another department points out a problem with the original plans for the project. You agree that this is a problem, but in order to fix it you would have to go back and start over from the beginning. You don't want to do that, so this is what you tell him.
At this point, I don't think there's much we can do about it.
"At this point" means "now". But you use "at this point" when it's too late or too early for something:
At this point the library is probably already closed. (too late)
A this point, all I know is that we're meeting some time on Saturday. (too early)
So when you use "at this point" it means "now" but also suggests that now is a bad time for whatever situation you're describing.
When someone is asking for help, but you can't help them (or don't want to help them), you use the phrase "there's nothing I can do".
Using this phrase makes it sound like you don't have any control over the decision to help or not help them. For example, if you are following a set of rules or if it's too late to make changes, you can say that "there's not much I can do about that".