How to practice vipassana meditation? I practice  vipassana meditation since 2008. My recent experience is  breathing can't be noticed. But sensation of the body is present. And thoughts are coming and passing away automatically. Most of the time sensation  of the body  appears such as pain , dissolves without any discomfort. Thoughts are less. Sound can hear but no thoughts on those sounds which were heard. 

What is this state?

How to continue from  here?
OP: My recent experience is breathing can't be noticed.


As you progress in meditation breathing becomes subtle and stops. As many prematurely think breathing has stoped when it becomes subtle but not completely stopped as one is not sensitive to detect it.

Breathing is tied to bodily formations.


  
  The in-and-out-breaths, avuso Visākha—these are states bound up with the body. 
  
  
  Therefore,
  they are bodily formation.
  
  
  Avuso Visākha, one, having first thought and pondered, then breaks out into speech. 
  
  
  Therefore,
  thinking and pondering are verbal formation.
  
  
  Perception and feeling—these are mentally-connected states, bound up with the mind. 
  
  
  Therefore, perception and feeling are thought formation.


Cūla Vedalla Sutta


  When a monk is attaining cessation of perception and feeling,  ayya, which states
  end first: 
  
  
  bodily formation, or 
  verbal formation, or 
  thought formation?
  
  
  When a monk is attaining cessation of perception and feeling, avuso Visākha, 
  
  
  verbal formation ends first, 
  then bodily formation, and 
  then thought formation.
  


Cūla Vedalla Sutta


  OP: But sensation of the body is present.


Perception and feeling \ thought formation is what ends last.


  OP: Most of the time sensation of the body appears such as pain, dissolves without any discomfort.


As you progress most of the sensations are pleasant but unpleasant sensations disappear fast.


  OP: Thoughts are less.


Thoughts/ verbal formation is what ends 1st. They initially reduce and subside.


  OP: Sound can hear but no thoughts on those sounds which were heard. What is this state?


This seems like a preliminary stage in meditation.


  OP: How to continue from hear?


Keep doing more meditation to go deeper. Double-check if you are practising correctly and have selected a proper technique which is conducive to you further in meditation.

Also, try increasing the number of hours.