And let's say he somehow manages to replace the money, either by means of borrowing or working menial jobs to raise the money, will his parents ever trust him again to save large sum of money with him?
He did a stupid mistake so probably his parents won't trust him again. But of course it can still change once he proved that he is not into gambling anymore and responsible enough by earning money on his own.
Assuming you find yourself in a similar situation as this, what will you do? How will you handle the situation to make your parents trust you again?
I will repay the money by working hard. It's a process to get their trust again thus it will take time. I will stand on my own, not relying on them and prove that I am worthy to be trusted again especially i'm their child.