have exhausted one's whole bag of tricks―at a loss as to what to do; at one's wits'end; at the end of one's rope/tether/resources; see no way out of the difficulty; without resorts
After he exhausted all possibilities, what remained in the bottom of the bag is escape.
He was at his wits’end: she would not listen however he explained.
There is nothing I can do about it.
He would be able to outmanoeuvre his critics.
Ag man, there's nothing anyone can do.