Accidental ahndball is not an offence = no free kick
Accidental handball is an offence = a free kick (or penalty).
From the laws of football
A direct free kick is also awarded to the opposing team if a player commits any of the following four offences:
* tackles an opponent to gain possession of the ball, making contact with the opponent before touching the ball
* holds an opponent
* spits at an opponent
* handles the ball
deliberately (except for the goalkeeper within his own penalty area)