Firstly dead ball in cricket basically means the time in between two balls. The ball being dead means the period of this ball has ended and the next ball will begin when the bowler starts his run up again. This is why they signal a dead ball when bowlers miss their run up.
Now then, as there no "dead-ball" which can be bowled, we need to understand what happens if a ball bounces twice or more.
MCC rules state that a ball may be called a no-ball if it bounces more that twice before reaching the batsman/popping crease. This means if it bounces twice it is a legal delivery. So in both cases whether bouncing twice or more if the batsman hits it, he gets the runs.
I see some people referring to Trevor Chappell's underarm ball.
Actually, as per rules prevalent then, an underarm ball was a perfectly legal delivery. Unsporting but legal. And therefore Trevor was right according to the laws. However, subsequently MCC and ICC banned underarm bowling and the rule...