I searched the web and found that it's a common issue with many Mac users. You are working and just like that it stops working. It does not click by pressing.

As a temporary fix, I went to
Apple > System Preferences > Trackpad and enabled One Finger - 'tap to click' option.
Now I don't have to click & it works fine just like other laptops.

But I need a complete solution for this.
If anyone can help, please suggest something.