Laptop hanging videos and working of laptop are hanging a lot, what i have to do now. I have re installed a new window and have updated it but the situation is same.

I don't think this is a software or OS issue but instead it looks like your embedded graphics chip is malfunctioning.
I am going to make a guess that you have an nVidia chip right?
What is the make and model of your laptop? There is a well known issue with the older nVidia chips that they would overheat and cause the solder joints to crack or separate from the motherboard. The fix for that unfortunately is to replace the motherboard or reball the nVidia chip itself (the process will likely cost you as much as a new motherboard though)

Most of the time if there are still hanging issues after a fresh windows installation, it means your hard drive is dying.

Since they have moving parts, they are one of the first components to die.

Heat would not cause your machine to hang.

Check for heating issues.. Make sure your intake and exhaust for your cooling fan are clear.. Blow out with air.. If fan is running hard and there is hardly any air coming from exhaust ports then you have a major blockage and either can disassemble it yourself of take it to a local shop/repair center.