cant connect to my instance

Just created a ubuntu instance, downloaded a .ppk

when I try to putty, using my .ppk and the public IP address, I get login as: I tried ubuntu, root, admin, ec2-user all result in "Server refused our key"

Can I create a new .ppk set of key or do I need to delete this instance?

When I try with the web-browser EC2 connect, I get the error "Failed to connect to your instance"