Depends on the rules you're playing by:
BCA rules state:
"4.17 - OBJECT BALLS JUMPED OFF THE TABLE
If any object ball is jumped off the table, it is a foul and loss of turn, unless it is the 8-ball, which is a loss of game. Any jumped object balls are not re-spotted. "
On the break:
"4.7 - OBJECT BALLS JUMPED OFF TABLE ON THE BREAK
If a player jumps an object ball off the table on the break shot, it is a foul and the incoming player has the option of (1) accepting the table in position and shooting, or (2) taking cue ball in hand behind the head string and shooting. "
Under APA rules, knocking an object ball (other than the 8-ball) on the floor is NOT a foul, and the ball is spotted when the shooter misses or, if it was one of his balls, when he has made all of his other balls.
HTH,
Walt in VA