> ssh -vT git@github.com
debug1: ······
debug1: Trying private key: /c/Users/YOURPCNOWUSERNAME/.ssh/id_rsa
Permission denied (publickey)

Need To DO,RENAME your privatekey to id_rsa,and add your private key to this directory /c/Users/YOURPCNOWUSERNAME/.ssh/*, so file locations is in this folder path /c/Users/YOURPCNOWUSERNAME/.ssh/id_rsa
Then,remember your privatekey PASSWORD and Enter it.
Note that the above operation is in your git repository directory.
reference link : https://help.github.com/articles/error-permission-denied-publickey/#should-the-sudo-command-be-used-with-git