I tried to build new droplet, I tried to use several different images, such ubutu 14, ubutu 16, lamp, lemp, phpmyadmin on ubutu, wordpress on ubutu, after setting up, I use Filezilla sftp to connect, but all got the same errors:

Error: Disconnected: No supported authentication methods available (server sent: publickey)
Error: Could not connect to server

Something wrong with the recently setting on digital ocean?

I tried methods on the forum, but none works. Please give a detail procedures to solve this problem.