I am from Pakistan. I am trying create student account but couldn't do that. One error came again and again i.e."The password/ID combination you have entered is incorrect. Please re-check your information and try again.". Please somebody help me to create student account. I will be grateful to you my whole life.

I think you can only use it if your university subscribes to it. If it doesn't recognise your address then it probably doesn't. Can you check with your university?

I have contacted the University, they said that you have to buy the account.. I couldn't afford it thats why I've asked help..

There's nothing you can do then, it's a not a free service, if your university doesn't pay for it then you will have to if you want to use it.