I use BitBucket and had to change my password because it was compromised.
remote: Invalid username or password. If you log in via a third party service you must ensure you have an account password set in your account profile.
fatal: Authentication failed for 'https://bitbucket.org/myusername/myproject.git/'
git config --global credential.helper osxkeychain
This resets the password in OS X keychain and after executing this, it prompts you for the user name and password for your repo.