I have read somewhere that He won't do something means He refused to do something and also He wouldn't do something has the same meaning.
Now I'd like to know, what is the difference in usage of these two sentences?
I checked the book Grammar in Use: Intermediate again and I found my answer:
You can use won't to say that somebody refuses to do something:
I've tried to give her advice, but she won't listen.
The car won't start. (=the car refuses to start)
Ref: Grammar in Use: Intermediate, 3rd Edition,pp 40-41, Cambridge University Press, 2009.
Somebody wouldn't do something = he/she refused to do it:
I tried to warn him, but he wouldn't listen to me. (= he refused to listen)
The car wouldn't start. (= it refused to start)
Ref: Grammar in Use: Intermediate, 3rd Edition,pp 68-69, Cambridge University Press, 2009.