Under what conditions will electric current flow through your body

You need two things:

- As you stated in your question, current has to flow through your body. So it has to enter and exit at some point. That could be touching two cables with different voltages (power outlet on your house has 120V and 0V/Ground) or touching a cable with high voltage and touch something else connected somehow to the ground. Also, did you ever notice that some birds just stand on some power lines and nothing happens to them? That is because current has nowhere to flow.

- The voltage has to be high enough to actually flow through you. Normally, one can feel some electrocution around 30V and above. But for some body parts it could be much less (ever tried licking the ends of a 9V battery?)

It's quite easy if you have a brain fade moment. I was tightening a power switch and forgot to unplug the unit first and grabbed the two live terminals on the back of the switch to hold it. No blue flashes but there was definitely blue air. 240V through the hand is not fatal but very unpleasant.

ever if a voltage > 0 is between two points of your bodyan electric current flows through your body. If the voltage is small, the current is small and you dont observe the current.

If you are standing on the ground, one of the above mentioned points could be ground.

when you touch the earth,the current flows through your body,in case you are standing on the hight insulated medium like dry air then electricity doesnt flows through your body

Whenever there is a potential difference between two separate points on your body.

All conditions. Unless you somehow make your body become 0% water, which at that point you're dead.