If your adsense account were ever to get deleted, would you have to pay back google all the money you earned?
Nope. That's like paying your employer all your earned money when you get fired or quit the job. When you have your money on your bank account, the money is yours.
It depends on the reason. If you violate the TOS... and that isn't up for you to decide, Google makes the decision... then you usually lose whatever you have on your balance.
You won't have to pay back the money you've already been paid out, but if there's a balance in your account (say $30 if you haven't reached the $100 payment threshhold), you won't be paid out that money.
I'm not sure if it's possible to "loose" money. I think what you meant to ask is if it's possible to "lose" your money if your account gets shut down and Sarah above me answered the question correctly.
for sure your all money will be lossed, because u've broken the rules, and in view of google all money is created with some trick, soo....