I have got a solution, i reffered to https://youtrack.jetbrains.com/issue/PY-20081#u=1468410176856.
Here they have tried to add https://pypi.python.org/pypi as a repository.
To add it as a repository,
1.) Go to Settings
2.) Project interpreter
3.) Click the + sign on top right edge
4.) Go to manage repositories,
5.) Press the + Sign, then add https://pypi.python.org/pypi
6.) Press Ok
Now all the packages should load.
Thanks Hami Torun & Simon, I was able to solve it by luck.