i am trying to log in to my account using github, it is showing authentication error. already user with the same email exists. i can go any further. even if i try sign up it does nothing. please help
hiya 
The usual solution for this issue is the following steps.
- Login to Netlify using the email address and password only.
- If you do not have a password configured, you can add one by using the password reset form .
- Once logged into Netlify with the email address and password, then change the GitHub account associated with this email address here: Netlify App
- Log out of Netlify.
Once this is done, you should be able to log into Netlify using GitHub or the email address. Both methods of login should work now. If they do not or if there are any other questions, please let us know.