Ball contacts the right spot on your bat

I have been playing table tennis for a long time but I am having a problem these days, Whenever I get high balls and try to Hit flat shots the ball clashes with my thumb and I lose the point and when the ball is chopped by the opponent and I try to hit topspin on it but those balls fall outside the table.

Hi Abhishek,

The main thing is to watch the ball carefully.  This will overcome a lot of your problems.

With the topspin try to make sure you are getting a good contact on the ball.  Sometimes the contact needs to be more of a brushing contact and this can be mis-timed and flatten out.