Hello

I accessed my server with ssh one time on from Ubuntu16.04

But when tried to connect next time I goy this error
“Could not open a connection to your authentication agent”
after executing
$ eval ssh-agent -s
$ ssh-add <path_to_private_key>

So I cant connect with ssh, and I don’t have login or password.
How can I get at least a login and password to access the server?

Please, help :)
I am new to Ubuntu