ubuntu - SSH authentification with public key fails

I have my id_rsa.pub key under my /home/user/.ssh. I carefully copied that key and paste my key to respository Git account.

While trying to connect from my local system to my git respository, I got the following error:

warning: Authentication failed.
Disconnected; no more authentication methods available (No further 
authentication methods available.)

I removed SSH in system and re-enable and did again, but no luck. I have no idea what's happening with my SSH key. Can any one please tell me on this?

Note : I noticed in my home /home/user/.ssh && /home/user/.ssh2