Lets say you started with a new venture, idea, product etc. I can almost 100% assure you that, there will be times where you face with problems that you never thought of.
It is not going to happen because you dont know the domain, instead you might be the best in that domain, yet world is changing, businesses are changing and actually the way we do things change.
That’s way i am 100% assuring you about facing hard questions to answer.
So what needs to be done in those times? Take a step back, take your mr. / mrs. knows it all hat off and start looking from another perspective.
You can ask yourself things like how would X approach to this problem?
There is a debugging method called, rubber duck. It worked and still works for almost every problem that i encounter. It helps you to talk to your innerself, looking thing from different angles and come up with a solution.
Go, try it out!