Further attempts (Rules 5.7.1, 6.2.1, 8.12, 9.1.4, 9.2.2)
You are allowed to make as many attempts to play the ball before it bounces twice as you like. This includes on the serve where you can make as many attempts to hit the ball before it hits the floor.
If you hit your opponent with the ball on a second or further attempt, you will no longer be awarded a stroke even if the ball is going directly to the front wall (you give up this right with the first attempt failing to play the ball).
If a good return is still possible but there is interference, a let is allowed. If a good return is no longer possible but an appeal made, no let is the result.
If the ball hits your opponent after you have made a first attempt unsuccessfully, you will get a let if you could still have made a good return on a further attempt. If you could not make a good return on a further attempt, your opponent wins the rally.